Five to eight sets of five reps for the squat. That way the training weight increases every week. It simply means that you should only put in as much energy for a particular lift as you need to. Ed Coan is a perfect example of that method. He seems to only put in as much power and strength as he needs for each weight.
Many lifters waste a lot of energy during their warm ups.
The ESM method is essential to the success of the 3x3 system. Considering that the training weights will be between 58 and 64 percent of your projected maximum squat, it is important that you don't put maximum effort in each rep and set. Just put in as much energy as you need to complete each set and concentrate on the perfect technique and the flow. With weights around 58-64 percent of your maximum there is no reason to psyche up. It is simply a matter of applying more energy.