It most certainly changes on some roads, usually to adjust timing for safe crossing. There's a street here that's notoriously wide for stupid reasons (parking in the median lol) and if pedestrians are around it gives them about 60 seconds. No button? Usually 15, but depends a little on time of day.

There's an interesting other case I've heard about from my Mom. There was a light that, at 3am, generally never changed unless a button was pushed. My mom had to get out of her car to push it every night after her night shift. I'm not sure that is still the case, but I suppose if your car never activates a sensor (or you're on a bike or motorcycle), it makes sense.