Yep, that's the best approach
It just takes a lot of time to explore the possibilities of techniques other people use and combine them into your own technique. As it has been pointed out, searching "coloring tutorial" etc on deviantart is the best inspiration, it just needs your time investment to go through the tutorials.
I think it's a good and quick technique that you can color your comic with. You probably know but it's goo to try varying the contrast between the shaded and lighted parts according to the atmosphere - sharp contrast in extreme situations, subtle in quiet scenes. If one screen layer doesn't do enough contrast, you can duplicate it several times.
For some enhancements you can try adding a line of highlights along the outline where the lightsource comes from (see the red scarf):
It pushes the character out of the background, doesn't take too much time and I think it would be perfect for your characters in suits.
I understand it too well, don't worry
I work on commissions all the time, I get sent to animation studios.... so I know pretty well what it is not being able to sleep for two and a half days (that's my limit), having to sacrifice some details just to meet the deadline... Some time ago I did a comic for a commercial campaign and for the last few episodes I had to sacrifice highlights because I just had to sent it in and I still regret it.
But when I can do a thing for myself, I love to immerse myself in the process 