I didn't say 2 seconds implies the use of momentum and poor form. I referred to what I have "normally" seen in gyms. Not that everyone uses poor form, but it seems to be the...norm. You were referring to "normal" in your earlier post. And if you're doing the eccentric portion of a movement in one second, chances are you're not really feeling it. You're still benefiting from the concentric part to some extent, but you're blowing off the negative.
How sore do you have to be for it to be meaningful? I have a bit or residual stiffness and mild soreness the day after, but it hardly registers. I'd have to be away from the gym for about 10 days or so for the soreness to be ~meaningful.
Too much, as in so much DOMs that you have limited ROM, will require many days off. You should have some soreness unless you’re truly at maintenance.
With minor exceptions, I've never had that kind of soreness. My best gains were made when I worked our 3 times a week with an ABA BAB split routine, so each muscle group was addressed directly 3 times every 2 weeks. This was in my 30s, although I maintained that routine well into my 40s. Even at my peak, those many years ago, when I was doing far more volume and frequency and going to simple concentric failure, I did not have the kind of soreness you're describing. Only if I added a new exercise or took some time off and then came roaring back at full intensity, did I get anything approaching what you're describing. And, for what it's worth, please believe me when I tell you that people commented on my intensity. So what was I doing wrong? Serious question.
Failure (for most) is the result of tempo. Most workouts are structured for rapid sets and concentric failure. You simply won’t get sore.
Presently, I go at a pace of at least 2s positive and 2s negative to concentric failure (and slower for some exercises), I keep trying at static for a few seconds, and then finish the set with a very slow negative for most of my exercises. Admittedly, my volume is much lower than it was those years ago, as is my frequency of only once a week (for resistance training), but my intensity has never been higher. I'm still not getting the kind of soreness you're describing. Any suggestions?
Since I'm only doing one work set to the kind failure I described, I want to get it right. So I rest at least 3 minutes presently between most exercises, and a bit more for the two exercises after which I do a single drop set about 15-20 seconds later (pull ups and parallel bar chest dips). I never liked short breaks between sets of a minute or so, let alone even less. It never felt right, even when I was in my late teens.