Drk full 1,2,3 single target combo is less viable than 1,2 target combo during filler

[Malthir]

So let me cook first and them flame me on how bad my maths is.

Hard slash, syphon strike, souleater leaves you dealing less damage in the minute window than just using Hard slash and syphon strike, as your mana gain allows for extra edge uses per minute which gives you higher damage output than if you use souleater.

Working off my characters current stats my GCD is 2.41s

Hard slash, Syphon strike 4.82s 600MP gain 620 potency can be done 15 times per minute, giving you a total of 9000 MPpm 9,300(11,600 inc edges) potency per minute

Hard slash, Syphon strike, Souleater 7.23s 600MP gain 1080 potency can be done 8 time per minute, giving you a total output of 4800 MPpm 8640(10,020 inc edges) potency per minute.

Surely I'm just being smooth brain and getting this wrong, or is it actually more viable to never finsih the single target weaponskill combo.

(Also want to state no third party tools used, all information comes from the in game tooltips.)