Should I do max OT training and cardio at the same time or 8-12 hours apart?

Max OT is a training theory/system devised by the sports supplement company AST (the makers of Vyo Pro - one of the first hydrolysed whey isolate products to hit the sports supplement market).

Max OT is basically a high-intensity bodybuilding training system that uses fewer reps per set and recommends going to failure on each set with short sessions in the gym. There is no evidence that it will work better or worse that the millions of other training theories out there. Certainly for some body parts, doing only 4 to 6 reps is probably not ideal, so I'm not a huge fan of this training concept.

Anyhow, as far as cardio goes, ideally you want to do cardio at a separate session with several hours between that and weights (don't get too caught up on how long between cardio and weight sessions).

If you're like me, you don't often have time to make two separate trips to the gym or wherever you do your cardio, so you have to do it before or after. Most guys think doing it after is best because 1) you've burned a good deal of carbs with your weight training and may therefore burn more fat if you do cardio after and 2) if you do cardio before, you may detract from your energy reserves and negatively impact your weight session.

On the other hand, some recent evidence shows that the activity you do second may achieve better training adaptation and benefit that aspect of your training. So doing weights after cardio may result in a better muscle-building environment in the body during recovery and adaptation.

So the answer is "no one knows" and until someone can find some kind of research that compares one strategy to the other, no one can say for sure.

Sorry I can't give you a definitive answer but as I said I don't believe this has ever been properly studied except in the roundabout way that I described above.