I tweak/fuss/whatever you want to call it. I think Wrath is too much of a gentleman to say that it drives him crazy when I give him a tree and then an hour later send him an "improved" version of it. He's lucky if there aren't 4 or 5 "improved" versions.
I've been tweaking the oak - did a much better oak bark texture. Moved a lot of the leaves around. Cut down the number of prims a tad. I think it looks better but I probably won't stop until I box it and it becomes too much hassle to make any more changes.
It's all an iterative process - continuous improvement. One of the reasons it took me days to make is that I made 3 different oak leaf textures. I thought mixing them would be good - but having built it that way decided using only one would be better.
Maybe if I knew what I was doing it wouldn't feel quite so haphazard. :)