I guess I'm old fashioned. I spend an obscene amount of time playing, stopping, backing up, and playing again until I've learned every part.
Oh, I do plenty of stopping and backing up, but there's a difference between trying to transcribe, say, a Geddy Lee bass line (which is usually fairly easy to hear) and trying to transcribe a Percy Heath or Ray Brown bass line that was recorded in some nightclub. Anything that makes hearing the bass easier will minimize the stopping and backing up.