Well, all else I can say is that in my experience, where I twit my strings so hard I've ripped bridges out of guitar bodies on several occasions (nerve damage means I have virtually no control over how hard I pick or fret, I'm either full-on or barely scraping the strings), I can go days and even weeks without having to retune a guitar, which I attribute to my very careful restringing technique. Locking, non-locking, fixed bridge, vibrato, tiltback, straight, high action, low action, thick strings or thin, never had a problem with any of 'em. Tuning stability has always been one of my top priorities and I'm glad to say that outside of a complete break, I've never had a single tuning problem on stage, even with cheap guitars and parts.
I've said it before and I'll say it again, if you're having tuning problems and there isn't obvious damage causing it (burrs in the saddle or nut, for example) then it's going to be down to how you're restringing and treating the guitar. You've got to be doing something severely wrong if you're having to retune a guitar every couple of songs. I murder my guitars and they're stable as a rock.