Our first travel trailer was a Dutchmen Sport Lite (total length 24 feet). It had no slides.
Our second was a Keystone Springdale TT (total length 31 feet). It had no slides.
Our third was a Keystone Outback TT (total length 35 feet). It had 3 slides. It was a rear living room, and both opposing sides were slides. It also had a slide in the bedroom, which was a closet.
Our 4th is a Keystone Montana High Country 5er (total length 41 feet). It has 4 slides. Front living - opposing slides - 2, Kitchen refrigerator and dining table, and the bed in the rear bedroom.
Dependability of the slides? I've never had a problem. It's just that simple.
But I think we followed a basic principle and never deviated from it. And that is the simple fact, the slides were (are) never extracted until the trailer is level and the stabilizer jacks, or the leveling system is on the ground. Only on a couple very rare occasions did we ever extend a slide while hitched to the tow vehicle. If doing an over night, I might have left the TT hitched, but only if the trailer was somewhat level, and then I'd always lower the 4 stabilizer jacks.
Second, I NEVER retracted the slides without sweeping off the slide roofs. NEVER. This safeguards small sticks, twigs, leaves from punching holes in the rubber seals, causing leaks. My current 5er has a ladder on the back and has a walkable roof. It's sooooo nice to get up on the roof now and use a long handled painters wand with a soft RV brush on the end and sweep them off, opposing using a 7 foot step ladder and having to reach over the top and try to keep the ladder stable on uneven ground.
Third, I treat my rubber slides a couple times a year with rubber slide cleaner, and this also affords an opportunity to inspect them carefully for damage. I've never found damage.
I don't know if these three practices are the secret to my success, but all I can say is, I've never had problems with the slides.
FYI... in a lot of ways, the non-slide trailers were less of a hassle. On the negative side, my wife and I played butt-bumpity-bumpity passing each other all the time. We don't have that "togetherness" any more with the slides. (I kind of miss that).
