Twenty Minute Challenge. If you haven't yet, visit--it's inspiring and a great boost if you're stuck or constrained for time.
I had a teacher several years back who would have us set up a two- or three-object still life on our desks; paint it in five minutes; then pass the objects to the person next to us and paint their objects ... musical still life. People in the class always groaned about it, but I loved that exercise, just as, in life drawing, the two- to five-minute poses were always my favorite: those short poses yielded some of my best work in the classes.
It's amazing how much you can learn in twenty minutes; the time really goes rather slowly. As I drew it I became worried that this subject was too complicated or detailed and almost abandoned it, but I decided just to push through the next nineteen minutes and see what I got. Without meaning to, I painted very wet and so lost a lot of the details I had planned to try to keep, like the pollen inside the crocuses (those purple blobs are crocuses) or the turnings of the dogwood petals ... Turns out, I don't miss them.
Next time perhaps I'll set something up with fewer objects, but here I'm pleased with how the wetness--which, in twenty minutes, you don't have time to work with, compensate for--solved the overcomplication problem.
I spent about one minute drawing and the last five minutes looking for things to "fix." I was tempted to soften the line on the jar at right, but my alarm had sounded, so I resisted.