Addressing the Training Volume Concern
In terms of what is "sufficient" for a sensible, productive training protocol, again it is impossible to state with exact precision how many sets / and or workouts are to be performed. What is beyond debate however, is that it cannot be a high number if one is true to exercise science and the literal definition of anaerobic training (resistance training, as an example) -which defines such training as "high intensity, short duration". The opposing branch is, of course, aerobic training (steady-state training)-by literal definition "low intensity, long duration". They are in complete contrast with each other, and are really incompatible if one is trying to reach the apex of his achievement in either approach.
While it is important to achieve a healthy heart-lung functional capacity, too much volume (amount) of work from an aerobic capacity standpoint when coupled with intense resistance training, will create an excessive stressor to the nervous system, which will prevent adequate recovery/compensation from occurring. This will prevent one from maximizing his or her potential in either pursuit.
There may be times during a particular training cycle when more total sets and repetitions are required, and more time spent in the gym is called for, but keep in mind that hormonal stress adaptations are always a consideration. Studies will show that exercising with proper intensity will command that one not exceed 40-45 minutes so as not to suppress the wide array of chemical reactions that provide for adequate recovery.
The harder one trains, the less he can and should train.
-Eric Shrieves