Life long hard gainer here.

Healing a cut on your finger and healing muscular trauma might be similiar in some aspects but they are different enough that one shouldn't be used as evidence of the other. A pretty poor analogy in my opinion.

I have never done any HIT training (which is a misnomer by the way) but I figured I would share my experiances with what was pretty much the opposite of a HIT/Mentzer inspired routine.

I had done a high frequency, high intensity program for 9 weeks, in actuallity it could be called 8 weeks with an additional test week. Training was 4 days a week, 3 exercises per workout. Day 1 and 3 I maxed out on the squat, bench and deadlift. Day 2 was a bench movement, squat movement, and another bench movement. Day 4 was a bench movement, some sort of deadlift accessory work and a bench movement. Overall there was very little variation in exercises. Intensity was kept high for day 2 and 4, without looking it up I don't think I ever went under 80% and most likely 85 to 90%. Some weeks I would train Mon, Wed, Fri, Sat and some weeks it would be Mon, Tue, Thu, Fri. Other demands in life dictated what days I would train.

My stats on day 1 was a 355 squat, 270 bench and 415 deadlift. On test day I squatted 395, benched 285 and deadlifted 450. This was without any weight gain, I had decided in the 2nd week to pause my weight loss efforts throughout the program. Another individual about of equal strength made similar improvements, a third individual was much stronger and was making progress at a slower rate and unfortunately tore his hamstring in the 8th week.

My overall point to posting this is the body can take a whole lot and still adapt to it. Many people would say the above programming would lead to overtraining, accommodation, and a host of other issues. And yet I stressed my body and then adapted to the stress regularly throughout the 9 weeks and became stronger for it. In order to continue adapting and improving it is going to take more and more throughout the years. Sure, at some point adaptation will require larger loads than what can be recovered from in a reasonable amount of time but that is a problem I believe very few people will ever run into. And don't forget that your ability to recover from workouts can also be trained and improved.

If you find training twice a week is what works for you due to lifestyle that is fine. If you simply don’t care to train more than twice a week that’s fine too. But the idea that you can’t train 3 times a week without seriously running the risk of overtraining is just silly and not taking into account the incredible capability of the human body.

I have done something fairly close, but not entirely.  Bench/Squat one day, work up to a top set, Deads/M press one day, work up to a top set. That was done 5/3/1 style. It worked really well until the squats and deads got heavier. It did not work for my bench towards the end, but 1/2 of that could have been because I wasn't recovering well due to the heavy squats and deads. If my lower body workout is too high, nothing works for my upper body.

I pay close attention to what I eat, and don't have unlimited access to food. I felt like that routine made the most of my calories, as I wasn't burning them up doing multiple sets and then trying to recover from them. I did make good strength/size gains for quite a while.

The only issue I have with doing 1 heavy set once a week is that I personally need a bit more to keep the movement fresh. That being said, it doesn't have to be a heavy set either, it could be dumbell bench instead of barbell, which would reduce the weight a lot.  

Do it to it! See what happens. A lot of people are surprised when they see what kind of gains they make when they actually give their body time to recover. For a while I was just going to the gym when I was fully recovered, which ended up being about 3 times in 2 weeks, and was making good progress on my bench, which doesn't usually move much. I am going to be going back to 5/3/1 simply because it makes the most of the calories you have available.

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MrKasab, while I am glad that program worked for you, it wouldn't work for 99% of the people that tried it. It probably wouldn't work for you again, either.  Putting 100lbs on your total in 2 months  isn't normal for any program, or any person, unless they are just getting started, in which case it has less to do with the program than the body's adaptation. Yes, your body can adapt, but only to so much, and it requires time and energy to do so.

I've been lifting weights since I was a kid. Read Heavy Duty when I was 16 and went right into it. Me, my bro and my best friend Greg. HEAVY. We made incredible gains. I literally changed my physique in 8 months. I trained with a shitton of intensity and I ate like a complete horse. Everything in the house was consumed. Dozens and dozens of eggs, all the milk, pasta even bagels. We'd eat wheat bagels dry and nap for 3-4 hours on the couch in the summer. Our lives revolved around it and we got serious results.
I am now a trainer and own my own studio here in NYC. I'd like to revisit Mike Mentzers Heavy Duty again sometime. That and the Encyclopedia of Bodybuilding laid the foundation for who I am as a trainer today.

Care to detail your old program?

I have found it I train one body part a day and try and seperate mucsle groups throughout the week I get the best gains. I keep my routine fresh by changing it up every 6 weeks or so. The latest change I have made is by pyramiding my routine. I have made some serious gains in the last 6 weeks, to the point the VP of my company asked me if I was juicing.  The key is not to over train a body part and to stop just short of that condition.

I remember that we made one set to absolute complete 110% muscle failure the name of the game. Feeling guilty we would add in additional more moderate weighted work in either before or after.
These were my first foray into leg training. I remember we would for example make ..Leg Press the big weight move so after 4 or so sets of medium weight full depth squats we would pile up the leg press and just keep stripping it down and spotting. Over and over until you couldnt lift the carriage anymore. We would roll out of the machine, possibly go throw up and not be able to walk for many days.
But We got strong and we got big and our workouts were short and intense..now where else have seen this- Short Duration...Heavy Weight..Focus on pure intensity..
Although lacking many of the 'total' components of Crossfit i.e gymnastics skill stuff, track and field etc etc - from a purely weightlifting stand point Heavy Duty was onto something.

I eventually moved into the heavy volume bodybuilding style of 20 or sets per bodypart. But the greatest increases in strength, stamina have always come from when I went hard and fast.
Today I did the Crossfit WOD 'Cindy'.
20 minutes of absolute hell. When ti was over I just wanted to go again, like a kid at an amusement park.
I love it.