You should be changing it about 1-2 months but then again changing the strings is one of the shittier parts of playing guitar. However, your guitar will go out of tune and loose its intonation if you don’t change them regularly
I have a Floyd rose on my guitars, so changing strings is an absolute chore. I’ve gone around a year without changing my strings and didn’t really notice a difference. I’ve learned to enjoy changing strings so I do it once my fret board starts to get dirty.
It depends on your budget. If you can afford to buy new strings every few weeks then do so. The longer you leave them though the more the strings will begin to oxidize, leaving them more prone to breaking. Plus the longer you leave them the duller the sound of the strings will become. If you don’t want to change them that often you can buy products from music shops and Amazon that you can apply to the strings after you finish playing. Skin oil, dirt and dead skin will be settling on your strings and neck. So removing this will help preserve the life of your strings a little longer.
I change mine every 2 weeks. Usually because I break my high e string all the time but also because I play a lot. I should probably invest in Ernie ball paradigms. But I’ve learned cleaning you strings after playing really helps extend their life.
When I was playing 2-3 hr rehearsals 3x a week with a band, plus gigs on the weekend and home practice, I would alternate changing strings on one every weekend, so with two guitars, they were changed every two weeks.
I play a LOT less now, and will easily go 6-8 weeks, then sit down and do them all (the 4 electrics anyway) at once. The acoustics I play a lot less, so I change them a lot less often – maybe every 6-8 months.
the oils and dirt from your fingers dull them and dirty and dull them giving them a “duller” sound over time. and if you use a floating bridge and do a lot of pulling on the strings it will cause the strings to stretch to the point to where they don’t hold their tension and wont stay in tune as well