And another reason a guitar goes out of tune is simply because too many use too thin string gauges. A saw a video on YT a luthier who work with ACDC and he said Stevie Young hit the strings very hard and therefore use 12-56 string gauge and they're playing in E standard. If you're a light picker then thinner string gauges are fine but if you pick little harder then you will benefit with heavier gauges and the strings will stay in tuner better and longer. I got a 11-49 set for d drop and have a 56 on low E on a Schecter BlackJack and damn, the guitar stays in tune better than any other non-evertune guitar I ever owned.
Just as an aside, it's key to note that the Evertune standard saddles are good enough for most people, but if you're detuned with light strings (or play in standard with unusually heavy strings, I imagine) you may have to spring for a lighter/heavier saddle set. It can be a little unsettling when you can't dial in Zone 2 correctly on one particular string, and while it only happened to me once the alternative in the short term might be to simply go for a different string gauge.