Guitar Strings

how often realistically should you rplace guitar strings, Ive seen it mentioned on here that you should replace them every 2 weeks which seems redicously often to me, but maybe there right, so how long should you keep one set of strings on the guitar?

keep them on until they become detrimental. if they sound fine, and play fine, there's no reason to change them. i use elixir, and they last for at least 2.5 months a set.

when they wont stay in tune and/or sound crummy,change them. lately
i've been getting about 3-4 weeks depending on how much i play.