Haha same, I draw from various angles and closeups so the panels feel dynamic and fresh. It's also harder for me since my style is different if characters are close-up vs farther away.
But I do copy-paste the main lineart if a character is facing the camera head-on by themselves.
This depends, but in dialogue-heavy scenes (which is... all of them right now, we're deep in exposition city) I'll reuse basic face shapes and change the overall expression between headshot panels. I usually copy and paste the sketch, but draw the lineart fresh each time. If I want to vary the angle, that's when I'll draw a new headshot from scratch.
That said, I will break up dialogue-heavy episodes with establishing shots, to make sure they don't get dull and same-y to look at. I also like to have the occasional panel with both characters interacting in it.
I also re-use background elements. Create an establishing shot, take a chunk of that background, whack a blur on it, and you have pretty, environmentally-immersive panel backgrounds!
Finally, I reuse full-body shots of characters standing or walking, particularly if they're reasonably small. There's no point in tediously redoing something so little, which few people are really going to linger on.
So yep, I 'cheat' quite a bit, but it's the only way to maintain my pace and art quality. If I did everything from scratch every time, my episodes would have to be far shorter.
It... depends on the panel 
I try not to re-use entire panels as they are (I did it once4 for lack of better ideas, but I'm kinda planning to change that page anyway)... however, if a character is going to be seen from an angle I already used once, I'm going to copy-paste the lineart to save time, change a few things (like the mouth shape or where the eyes are looking)... and then recolor it all from scratch. I used to copy-paste the sketch and redo the lineart all over again, but then I figured... why waste time when I just need to change a couple of things? :'D
I also have a bunch of "premade assets" that I put together to make backgrounds and save time. For example, the cemetery seen here1. I made a version with the tombstones and one without, so whenever I needed to add just a bunch of trees behind the characters, I just copy-pasted them. The statue here1 has been copy-pasted a few times too, because let's face it, it was a pain in the butt to draw XD Tombstones, bushes and trees also got copy-pasted from time to time. The tree from panel four here is actually a mirrored and slightly edited version of the tree seen here, attached on top of my premade "cemetery background".
I work traditionally and draw every panel from scratch. I rarely have panels with the exact same layout, but sometimes it's necessary to give a storytelling effect. That said, I don't think it's necessarily lazy if someone copies the previous panel directly. We all work differently. The important thing is that the finished product looks good and effectively tells the story.
I've done this a few times - usually just copy the whole damn thing, hide colors, adjust lineart, then fix up the coloring/shading. Sometimes it's been lovingly done for effect and sometimes it is blatant, looks shitty and done just to save time.
My personal take is that we're making our comic with two goals: to entertain anyone that follows it and to learn how to make a comic. When I get in the situation where I end up taking obvious lazy shortcuts, usually I'm trying to balance:
At the end of the day it's ok with me to make trade-offs between those points.
I reuse panels if there is little to no change before or after the next panel. It saves time and avoids me having to rack my brain on how to make it different and just focus on making the other panel different. It only happens here and there, though.
I copy+paste liberally when it comes to comedy comics. ^^ Normally it's just one character/half a panel, but occasionally I get to copy+paste whole panels with very minor changes, and that's always fun:
Although I think with comedy, especially in a simple art style like this, copy+pasting is more of a legitimate technique than just laziness or a time-saver. Like...the point of this visual gag is for the character to not move; to grudgingly accept the kiss and just silently simmer in fury. ^^ I could have drawn them organically each time, for its own sake, but it wouldn't really add anything of value to the comic.
With more detailed and serious comics, though...I actually lean towards 'explicitly trying to avoid having panels with a similar layout'. I don't have any disdain for the strategy; if you can use it without having panels look cloned, more power to you. It doesn't really work for me, though, since I'm not a 'full' digital artist.
Like, things like drawing whole libraries of pose 'mannequins' ahead of time and just pasting them in and drawing the character features on top...or even just copying one pose and reskinning it to be a different character-- as convenient as it would be, I can't do stuff like that. ^^; The time it would take to 'dress up' one mannequin with my pen-mouse would greatly exceed the time it would take to just draw it from scratch. Might as well make everything unique...
The only exceptions would be if the two characters look very similar (like in DotPQ...I talked about that in the extra material), or if they're drawn so tiny that all their features are just vague blobs anyway. :6
It WOULD be possible for me to take a pretty panel and use it in a later location with a different background and lighting...although I haven't had a chance to do that yet. ^^; Maybe someday, if I find I need a last-minute spacer panel...
There are times where I'll copy a panel; there are times where I'll copy a panel and add subtle changes- like an open or closed mouth, changed facial expressions or hand gestures...then there are times where I'll render the background, copy it and change the movements/gestures of the characters from the previous panel to the next.
I do it more as a form of storytelling/usage of time technique between panels as opposed to saving time.
I'm honestly a bit surprised to see that a whole third of people prefer to clone&edit an already finished panel. I would imagine it would be harder to try to not destroy the panel with your additions, than just draw it from sketch anew.
Layers are my friend in this situation. When I go to change the lineart, first I copy it and set the "old lineart" to low opacity so I can still see it (or hide completely if I don't want to use it for visual reference - either way I still have that version available). Then make changes on the copy. If there's enough to change for flats or shading I can just hide those layers and use fresh ones. Usually lighting/overlays stay more or less the same... nothing gets destroyed if you're organized about it.
I also try to reuse panels as little as possible, and when I do reuse, I like to rotate and zoom a bit, draw over some stuff like hair, and make it feel like it was meant to be similar as part of the joke. Also I enjoy the liquefy and warp tool which allow me to sort of shift something in perspective a bit, not a ton, but enough that it's different.
@Darth_Biomech TBH I totally messed up and clicked that option instead of copying linework only and then just repainting it, haha.
i do my best to make the panels look similar though i do sometimes change the "camera angle" so it never gets to tedious
I penciling and inking traditionally, so i just draw another one. Unless there's 3 or 4 panels with same camera angle + complicated backdrop. (maybe 1% of that situation)
So far the most I've copied was some lines (I'm... really bad at drawing symmetrical faces head on, so I was copying+pasting my character sheet and then making adjustments before inking). I don't look down on duplicating or anything like that, I'm just trying to be economical in my pages so... I rarely have duplicate panels.
I copy-pasting the whole panel if possible. But if I have to make a change I do it in the original panel (copy the page beforehand) before export-import it to the new panel.
I don’t really tend to copy entire panels, but I will copy the sketch for backgrounds if the two panels are at the exact same angle and place. Characters I draw from scratch each time.
Sometimes re-using a panel can be good for joke, or expressing that a scene is moving very slowly. That's about the only time I try to use them.
The majority of the time, I don't/can't straight copy and reuse panels, BUT WHEN I CAN I'll do it. No use doing more work when making comics is already so time-consuming. 
Like these two panels are several pages apart, but it's literally the same panel xD
These are different chapters but the action was the same, to I copied the lineart, lol and only changed it to fit some minor style changes
Reusing backgrounds is the easiest imo. I know I have more examples of me copying the bg, but I don't remember which panels are copied atm.
