When it comes to muscle SIZE (hypertrophy), tension is key. Both time under tension and intensity of tension.
Interestingly the Big 6 Exercises aren’t necessarily the best possible exercises when it comes to size. Some, like deadlifts and rows, have a poor “stimulus:fatigue” ratio. You get tired from performing them before you get enough volume to hit the time under tension.
This isn’t the most ideal for building raw strength, but is for bodybuilding stuff.
Additional factors:
- Proper form & tempo
- Lifting to failure more often
- Progressive Overload in all its forms