You have discovered (because you have a mind to) what I discovered years ago. I was training 1 1/2 to 2 hours a day 6 days a week, that's almost 12 hours of exercise a week. This did not include drive time and showering and changing. I had modest improvement at first but gains always slowed and I saw very little in strength or muscle. I did this for around six years. Then one day we received a new chrome line of Nautilus into our club. I laughed at it with the other muscle heads. stating of course that this is for the weak and not for serious lifters. Oh how wrong I was.