Where I live, the temperature will certainly fluctuate, but it stays relatively constant in my apartment most of the time. With that said, my basses don't go horribly out of tune very often at all. Are they completely in tune all the time? Absolutely not. But they're in tune to themselves pretty close, and enough that I can pick it up and play for practice and boredom without needing to use the tuner each time. It's typically pretty close, though not 100% dead on. If I actually need it in tune, then of course I'll tune it up, but it's not too often that it needs tuned for my use. I'd say I probably do a "proper" tuning (for lack of better words) once every 2-3 weeks at most, often times longer, assuming they tuning pegs don't get knocked out of tune.