many read or "skimmed" doc's research a nd have mis interpreted or mis quoted for a long time.
EFOC is just ONE Of many variables one is able to control to IMPROVE (not perfect) penetration.
Tuning a bow and arrow, or arrow to a bow (both are equally do-able) is critical. EFOC is for those of US who believe it helps with those odd situations we have encountered that limited penetration or --worse--- and wish to avoid.
Personally, age related ailments made me lower draw weight so I looked for way to increase penetration. EFOC is one of them, but not something that fits all situations!
Tune, have confidence and "pick a spot".