The answer is it depends. Some professional guitar players change them for every gig. In general, for uncoated strings on average around every 1 to 2 months as a rough guide. For coated strings, players report wildly different time intervals between string changes, but certainly much more prolonged than uncoated strings.
You might be wondering why all guitarists don’t use coated strings. The answer is tone; some players detest coated strings because they dislike their sound. Others love them for their tone as well as there longer life.
Coated strings are more expensive but last longer. If you are one who hates replacing your guitars strings, coated might the best option for you? Particularly if you have a lot of guitars. It’s important to wipe your strings regularly as you play, especially if you’re playing in a hot environment and you have sweaty hands.