There's no single correct answer to how often you should change your strings, but there are some good rules of thumb, along with a few habits that will help them last longer in the meantime.

Signs it's time for a new set

Strings rarely fail without warning. Look out for a duller, flatter tone that doesn't brighten back up after tuning, visible discolouration or grime built up along the wound strings, difficulty staying in tune, or a rough, gritty feeling under your fingers as you slide between frets. Any one of these is a reasonable sign it's time for a change.

How often, roughly speaking

A player practising daily might change strings every month or so, while an occasional player could reasonably stretch that to every few months. Strings also age even when a guitar isn't being played, since sweat, oils and general humidity affect them sitting in a case too, so time matters almost as much as hours played.

Minimising string breakage

Most string breaks come down to a handful of avoidable causes: sharp edges at the nut or bridge saddle that gradually fray a string, corrosion from sweat and moisture building up over time, or simply strings that have been left on far longer than they should have been. If you're breaking strings unusually often, it's worth having your guitar checked, since a rough spot at the nut or saddle is a common, easily fixed culprit rather than bad luck.

Cleaning strings between changes

Wiping your strings down with a dry cloth after each session removes the sweat and oils that cause the most damage, and takes seconds. Some players also use a dedicated string cleaner, which can help lift built-up grime from wound strings and extend their usable life a little further. It won't make old strings sound brand new, but it slows the process down.

Do you need to remove all the strings at once?

No, and in fact it's generally better not to. Changing strings one at a time, rather than removing all six and leaving the guitar completely slack, keeps a more consistent load on the neck throughout the process. It's a habit worth building, particularly on older or more delicate instruments.

The bottom line

Let your ears and fingers be the real guide rather than a strict calendar. A dull, hard-to-tune, gritty-feeling string is telling you something, and fresh strings are one of the cheapest, most noticeable upgrades you can make to how a guitar sounds and plays.