I shoot for perfection, knowing it isn't happening. If I get close, that's close enough for me. I doubt I will ever enter a quilt in a show. My quilts all go to someone I love, and they are thrilled to have something I have put my time and talent (?) into. If something is WAYYY off, I will take it apart and try again. If that doesn't fix it, that block ends up at the edge of the quilt, or in the orphan block pile, depending on how bad it is.
This is a hobby, and I do it for fun, and the satisfaction of giving a gift to someone. If I don't enjoy it, why bother?
So in short, yes, you probably are too critical. Try to relax a bit. If someone gave you the quilt with the blocks that were nearly perfect would you use it? I bet you would, and would never notice those "customizations" again.
Darren