Fred, you might agree in the fact that intramuscular stimulus based in continued tension (such as isolation drills for the erector spine) can contribute to the the improvement of inter muscular or compound exercises (such as deadliest).
However, based on my own experience i can tell you that isometric contraction provides more endurance strength, while, at its best, eccentric strength is stimulated by tempo under tension; and, concentric strength increases when improving starting, explosive and acceleration speed. As you well educated opinion revealed, you might be familiar with numerous scientific protocols that back up such conclusion.
For instance, Hypertrophy of the abdominal musculature, as it happens with muscle groups in general, can be stimulated by performing sit-ups on a swiss-ball while holding a heavy load under continued but alternated extension /flexion of the spine. However, isometric contraction under continued compression, while performing drills without joint movement, such as the plank, will provide extraordinaire endurance strength but poor hypertrophy (isometric contraction can increase muscle mass within rehabilitation scenarios but squeezing their lats while posing down was not what gave Yates, Haney or Coleman all that gigantic mass… By the way, as much as the 1’20” plank world record established by George Hood is a remarkable effect, it reveals a massive extensive endurance strength but far away from increasing muscle mass).
Taking your reps to failure is useful under the right circumstances and in the right doses. And it's not the only stimulus for growth, maybe not even the best one. Granted, there's been some research showing that the weight used isn't as important as going to failure when it comes to hypertrophy. We've covered this before in the The Single Best Muscle-Building Method . One experiment even showed that a load of 30% of a lifter's max (light weight) led to similar hypertrophy as a load of 80% (much heavier). This would indicate that failure is required in stimulating growth. But nothing is ever that simple. You can't ignore all the bodybuilders who've built a lot of muscle without going to failure.
When training the back, you can’t forget to utilize pull-ups and deadlifts. Where people go wrong with these exercises is going too light, or doing too many reps. Pull-ups and deadlifts produce the best results when done with a heavy load and low-reps. I have found that around 5-reps produces some great strength gains, as well as thickness and overall mass in the lower-back, lats, and upper-back. The machine row is also great to utilize when trying to go heavy. If you go too heavy on bent over rows, you are likely to use poor form and risk throwing out your back. The machine row is perfect for heavy weight, time under tension, and lowering the risk of injury when using heavy loads.