This is starting to worry me, then. I've been on SS for what seems like an ungodly long time (6 months) but I'm still making gains. One part of me says "if it ain't broke, don't fix it," but I hear stuff like this and I worry.
I have the sense that, at least in my case, SS is good for strength on the major lifts and not so great for looking muscular -- which is occasionally disappointing but basically fine, since I'm mainly going for strength. (The dream -- tentative right now -- is to do a powerlifting competition a few years down the road.)
I'd like to go until I get the typical 1xbw bench press, 1.5xbw squat, 2xbw deadlift, and at the rate I'm going I should hit all of those this summer. (It's taking me this long because I started very weak, not because of lack of progress.) Does that sound reasonable or is there something else I should do instead?
(I haven't been totally strict about the 3x5 because there have been a lot of days when I wanted to work up to a PR where I couldn't do that kind of volume. And I move up in weight about once or twice a week, not three times a week, but as I remember it's pretty much always been like that, so I don't think it's "stalling.")