I'm mainly a beadweaver, so there is a lot of time invested in a finished piece and I rarely take one apart, although bits of it might get re-stitched several times during the making process. Even if I don't personally like the result, if it's wearable, comfortable and finished to a high enough standard, then it's a 'keeper'!
I have learned to be loyal to my initial idea, as very often I get half way through a 'big' piece and absolutely hate it. I have to make myself carry on and work through this stage, as most of the time the finished piece turns out fine!
From time to time I have heroic failures, or I make a mistake somewhere that can't be unpicked, or the finishing on a piece isn't up to scratch, or it isn't quite reliable or strong enough to be saleable. These pieces either end up in my personal beadwork box (which is overflowing!) or are offered as swaps - and I'm very lucky to have a lovely friend who collects my work and will give a loving home to my sub-standard pieces in return for beautiful lampwork beads!
I do have a 'recycling' box of bits and samples, but quite when I'll get round to 'recycling' it I don't know - unpicking seems to take forever!