John:
Just read you post, and know your feeling. I, too, have struggled with resource material that ran from so-so to terrible. Fortunately (so far, at least) it hasn't mattered that much because I was doing some "odd ball stuff" for my wife. She has several brothers who fought (some died) in WWII, and asked if I would paint vignettes from old photos, one of two of which were black and white.
Yikes!!! For no reason I can pinpoint, some went well, some went so-so, and one or two were just as awful as the old photos.
As for getting down to the finish of a piece . . . my progress seems much like everyone elses -- fast at first, and then slows as finish approaches.
I'm sure this has to do with the fact that first few days, I'm just laying in big shapes, colors and values. It is when I start adjusting within shapes, colors and values that it begins to get complicated.
Also, the longer I do this, the more I amaze myself to find that I can usually work another week (maybe more) after I think the painting is finished. I'll put down my brush, sigh, and say fini. But, the next day, I decide to work just another hour, and find I've put in another day on the thing, with the same thing happening the following few days. I begin to wonder if a painting is ever really finished.
I recently watch a video by a guy named Jay Moore (
www.jaymoore.com, I believe) in which he points out how the eye sees, which, as you probably know, it sees less and less as our peripheral vision drifts farther from our point of interest. He also makes the point that if you look at portraits by the old greats -- Rembrandt, et al -- you'll see that this is how they looked at and painted their subjects . . . with the outer areas going softer and grayer. It's a point to remember when you feel you've "lost it" over in one of the far corners of your paiting.