There are two guidelines you should follow if 1) you lift hard and heavy and 2) you're an experienced lifter.
1 – Don't train more than two days in a row.
Even when the goal is to maximize muscle mass, the program should be based on getting stronger in the big basic lifts. To put your body in the best possible position to perform them at a high level every training session, it's best not to train more than two days in a row.
Yes, it's possible to train more often, but your performance will suffer on that third workout. The only way that'll work in the long run is if one or two of these workouts are fairly easy. If you plan to train hard at every session – doing big basic lifts plus assistance work – you should avoid doing more than two training days in a row.
Remember, it's not about how much you can do and get away with; it's about performing at the highest possible level every time you walk into the gym. If you have no shot of improving in some regard during a workout, you're wasting your time.
2 – Don't rest two days in a row.
After coaching high level athletes for years, I can say this with certainty: When athletes are given a Monday/Tuesday/Thursday/Friday workout schedule, the first workout of the week will always be their worst one. You'd think that after the weekend they'd be well rested and would perform better. Not so.
Even though a person is physically rested, performance suffers because the nervous system is more sluggish after two days off, and it's harder to get the nervous system excited/activated during the session. That's why under normal circumstances (barring illness and injury) I highly recommend never taking two days off in a row.
How to Apply the Rules
Try this schedule:
- Monday: Training day 1
- Tuesday: Training day 2
- Wednesday: Off
- Thursday: Training day 3
- Friday: Off
- Saturday: Training day 4
- Sunday: Off
That is the training split that'll allow you to have the highest number of maximum quality sessions in your week.