Logitech G502 microswitches

not sure if the g502 uses omrom D2FC-F-7N for the main buttons but it does use omron brand switches for the side buttons.

generally you should get at least 3-4 years out of them before they start to fail. switches are replaceable as well and can be had for under $1 each. a little soldering and you're good to go.
 


Can't emphasize this enough IMO, if you find a mouse you really like and are comfortable with, it is well worth it to repair in most cases. I've repaired a few over the years. Switches fail for a variety of reasons (in a variety of ways too). If you find you mangle the "feet" getting to the screws (I haven't yet, but...), replacements can be purchased for those also
 
i have two deathadder 3.5g models. one purchased in 2010 had the double click issue happen this year. i have it sitting on my shelf needing to be fixed but given that i found a new-in-box one for $30 i picked that one up. i'll eventually repair the original so i have a spare but i've been busy lately. taking it apart was easy and replacing the switches is also easy if you have basic soldering experience.

i cannot say about the newer models although i think they all use the same switches (though do not quote me on this).

there is no set time that a mouse is supposed to last. i've gotten 6-8 years out of mice before and as little as 2-3. the switches used, how much you use them, how often you click and how forcefully you click can all affect switch wear. if you're very aggressive with mice you could be prematurely wearing them out but honestly it is hard to say and this is just speculation.

as for my own usage patterns - generally at least 4-5 hours daily. mostly web browsing with a little gaming, photoshop and other tasks mixed in. this amounts to moderate usage levels in terms of clicking.