Progressive overload and going to failure need not be linked for results, in either size or strength. If the body is given a proper training stimuli, and a fair recovery period, nature pretty much takes it's course. Being that the CNS (the key to all) will meet that stimuli and adapt, and progress (muscle/strength) to meet the newer stress factors. Of course, training hard does not mean going to complete failure in most training sessions. That will attack the CNS badly.
Glad to see that dj181 has experimented with 8X8's & 10X10's. Most people who attempt these styles will lose a bit the first week or so. Than the body kicks in, producing results at a fairly fast rate. Or some drop out the first few workouts because of the physical, as well as the mental, efforts involved. Sorry that dj181 did not experience any favorable benefit from such training. Nothing works for everyone.
I've given high school/college football players, who needed to gain 10 to 20lbs off season, GVT and for the most part gains of pure muscle mass and strength was achieved (usually between 6 to 10 weeks..the first week or so is a breaking in period, which trying any new systems require). Than they went back to regular football training workouts. The GVT workouts might include cleans, squats, jerk presses, benches, Hi-pulls,etc. Most effective one exercise per body part was the squat clean, a true mass builder. Some times including the jerk overhead. Good Luck.