Some of this honestly comes from practice. It sounds like you're not speaking from experience here -- have you tried out making comic pages, for practice? That's a worthwhile thing to do!! The first pages you make probably WILL take forever, just because it's something you've never done before, but once you get the hang of it you can see which parts of the process are big time sinks for you.
Keep in mind also, that More Detail doesn't automatically mean Better Art -- it's definitely possible to have simple art that isn't mediocre! You can be specific in your choices without also going overboard -- for example, adding a bunch of fancy moulding and detail to the chairs in your protagonist's dining room doesn't necessarily make the panel better, but thinking about what kind of chairs might be there rather than just drawing a vague rectangular lump will help a lot.
Last thing I'll say is that different techniques work for different people. Some people are fastest when they're picking colours out of their head; some people are way faster using swatches and throwing some layer styles over the whole thing. Some people skip straight from loose roughs to inks which helps their drawings to be lively and fast, but for me to do that would be slower, because taking the time to draw tight, planned out pencils lets me ink more quickly. So a lot of this is gonna be, drawing some pages, trying it out, and finding out what method works the fastest for you!