You say you compose & commit to sounds early on, and mix later. How do you know if a particular sound is going to stick and work when it's not part of a "cohesive mix"? Hope that question makes sense.
It's always part of a cohesive mix. I don't work on sounds in total isolation - they're always in context and I'm shaping them to fit their surroundings, and vice versa.
I'm constantly tweaking the monitor mix and while working on a synth sound I'll regularly get sidetracked and spend an hour sorting out the percussion because it's not sitting right with the sound I'm working on.
When I'm happy a sound is 90% where I want it to be I'll commit it to audio and move on. It can always be processed further and if I'm unsure or the sound is particularly troublesome or important I'll save the pre-bounce project under a descriptive name so if I ever need to do the bounce again I can just load it up, make the changes and re-bounce.
To date this has never happened.
Committing to the sound when it is done stops me endlessly fucking around with it and means I actually get stuff finished as opposed to having a hard drive full of unfinished projects.