HIT is pretty much the primary reason why the majority of people in gyms make no progress
I have no idea what Andy's training looks like or what he looks like lol so I can't comment on that but he says that it's worked for him
In another thread we have a discussion announcing that if you're not progressing then you're not pushing hard enough, now you're saying that the majority of people fail to make progress because they push too hard within each set?
I think the reason the majority of people over 25 (and females in general) don't make any progress is because they don't try, they don't have any planned progression, their exercise technique is crap, their program is a random list of exercises and/or their nutrition sucks. I think the reason the majority of males under 25 don't make any progress is a combination of all of the above except for effort. Young boys will try hard, but every other component will be craptacular. Also, while they'll be trying hard, it'll typically only be on bench press, curls, maybe pull ups, maybe crunches and maybe leg extensions.
HIT isn't the reason the majority of people get nowhere. The people who actually understand and follow a HIT program usually understand the other factors as well, at least enough to make a difference (nutrition, exercise technique, a balanced program, etc). I'm not anti-HIT. I'm not pro-HIT, either. It's just a way of training. But the idea that a lot of HIT enthusiasts will promote with the way they train is a bit like 20-rep squats, in that they're going beyond the regular point of failure if they were to just rep out the weight.
For an exercise in a regular volume program, stopping a couple reps short of failure, you might do 3x8x100kg for a given exercise. On a HIT program, you might take that same exercise and that same weight, and do 10 reps to concentric failure, then 6 eccentric reps with spotters doing the concentric for you, then hold for 15 sec until you can't stop the weight from coming back down. All other variables being equal, which of the above two training options would promote greater hypertrophy? I don't know. I don't claim to know. But I'm not so quick to dismiss what actually makes HIT, HIT. I think that the relatively low volume and low frequency compared to other options (which, btw, is not a requirement of HIT) that is common in HIT programs is more likely where the training style may run into problems, rather than the actual training techniques used.