EF buffs mastery, and is required to use prior to FW heals
Fist weaving lego gets zero benefit from mastery, and thus also zero benefit from the EF buff
FW has downtime during the healing windows, as you are building up stacks - these make it less suitable for keeping the group topped up during moderate damage (ie grievous stacks will be building, etc) and it prevents you from precasting your high heal ramp up abilities (EnV mostly, and ReM - though to a lesser extent) so you are less prepared for ramping damage (expected or otherwise)
The combination of downtime AND randomness mean it isn’t reliable during heavy damage either (forcing you to EnV and Viv cleave), best case is you dump a couple kicks at the end of the FW buff window to top people up.
The only real case it is useful is if there is basically zero aoe and a single target taking moderate damage. (So the damage to heal isn’t wasted) BUT we are required to EF BEFORE so basically using it to ONLY proc the FW buff
If everyone is at low health and taking damage, then random healing, while effective in terms of utilization, has no guarantee of keeping up the lowest/highest risk of dying players.
This puts it in a place where, in actual SL gameplay, it is basically overhealing when the group is topped up or too little to late.
The throughput is good in a raid environment, I’m. Not saying it isn’t putting out healing (plus it sidesteps the mana issues brought back with the removal of essences). It has its uses - but it is clunky as F