I'm gonna add to a couple of points that have already been mentioned.
1) High Intensity Training requires absolute, 100% mental committment. There are very few people on the planet who can push their bodies hard enough to reach momentary muscular failure. And only with true momentary muscular failure can you call it a maximum set. That's why you hear people like camarosuper6 mention "higher volume HIT". This, in my mind, would be a better way to go because it increases the likleyhood of truely exhausting the target muscle 100%. You're still limiting the time you're in the gym, but you're guaranteeing you get a complete workout. Instead of one "maximum" set, do two.
2) You mentioned you're recovering from a shoulder injury. One of the downfalls of HIT is that it is VERY hard on your joints. I myself have had knee surgery from getting stupid with squats so I'm speaking from experience here. I firmly believe in HIT because it's done wonders for me, but you have to be careful and pay attention to your body. By being careful, I mean you have to use PERFECT form. During HIT you're dealing with much more weight so you can hurt yourself faster than you can blink an eye. Perfect form is your only protection against injury. By paying attention to your body, I mean you have to pay very close attention to every little twinge and tweak. There's a huge difference between giving yourself sore muscles and doing damage to your joints. Pay attention to which is which and know when to back off. Once your joints start to hurt they will NOT stop until you give them a chance to recover. That means ditching the HIT routine for a while and going to lower weights and higher reps. Dorian Yates did that a few years back and discovered he made tremendous gains during his "recovery" periods.
