10x3 or 12x1

I previously researched, and posted, about how many sets and repetitions one should use when working out. I started my workout routine in February based on what I discovered and used 1 set of 12 repetitions to muscle fatigue.

While this appeared efficient, and initially saw gains, I'm not seeing gains now. Today I decided to try the 10x3 approach to see how different it would feel. Of course, I thought I wouldn't be able to use the same weight for the 10x3 as I used for the 12x1. It appears I've been short-changing myself and not pushing as hard as I should. For every exercise except assisted pullups I used the exact same weight as I used previously.

Friday's Workout:

Assisted Dips: 10x3 at lvl 12 (weight unknown)
Assisted Pullups: 10x3 at lvl 16
Seated Chest Press: 10x3 at 110lbs
Seated Overhead Press: 10x3 at 110lbs
Cable Crossovers: 10x3 at lvl 6.5 (weight unknown)
Standing Calf Raises: 10x3 at 75lbs
Seated Flys: 10x3 at 87.5lbs
Seated Rows: 10x3 at 137.5lbs
Camber Curls: 10x3 at 50lbs