as soon as I noticed the strings sounding dull I would change them-sadly that would usually be at the beginning of a practice, so I'd also get practice switching guitars mid song; I was using 14-56 strings at that time...now with bass it's about the same thing, strings sound a bit dead and I break one...I always change strings before a gig now as I rarely gig, but if I was touring I could probably go awhile on bass strings...I would likely change them more than I need to though, as I love the sound of fresh stainless strings; my frets do not though, and am facing a refret in a year or so...Tony