higher volume not producing results?

[Noah Wixx]

I was doing 5-6 sets of 15-20 reps a set for a long time and it was burning me out, once I dropped down into 1x15 warm up set and 2x10 or 2x12 for my working sets I became much more efficient and I got alot stronger and pretty quickly, the results have definitely followed dropping into what I am doing now