I will have to pay closer attention in combat as well , but if this is true , then it really sucks . Normally , i am albe to use Energy Overload for an extended period of time , going through packs of 6-7 mobs ( i use Lightning Form for the protection and watch them fall ) and still have some left for an other short one afterwards.
If the Ultimates that don't have a togle consume all your resources even though the tool tip sais , it consumes x amount then , its either a bug , or if it is intended , at a later date in the game's like , they should update the description to match the cost , or say : drains you ultimate resource completely , to use this ability.

ThatHappyCat wrote: »

It's definitely intended. Otherwise people could store up a bunch of Ulti on mobs and then unleash say ten consecutive Crescent Sweeps on an unfortunate soul.

I would hate to be that unfortunate soul. But like stated, it is intended for that reason, the displayed ultimate is just the minimum amount you need to execute the skill. Ultimates that have low costs and drain ultimate (i.e. Overload) can really shine with this.