Science of pump sets

[Machmood]

I follow brad shoenfeld and he regularly talks about the components of hypertrophy. In FT, the pump set is to achieve some metabolic stress and to an extent muscle damage( also I believe to be able to hit a muscle 3x a week and not burnout , so some sets need to be light) anyway my question is that although a 20-30 rep set with give some metabolic stress, it seems metabolic stress is built over time not a single exercise. Meaning throughout a workout you build up more lactic acid and continue to get a better pump. Things we do for pump sets usually come after a workout to induce MORE metabolic stress, not nessasarily on its own. My question is how effective is just 1 , Maybe 2 of these sets for getting this job done??