Originally Posted by
TouchandFeel
Don't get in the bad habit of "saving" your abilities just for boss fights, use all of your tools as much as you can, as best you can. Seriously, boss fights in dungeons are so easy that there is no pressing need to "save" anything for them. Most abilities, such as Req have such a short cooldown that even if you use it during trash, it should be available by the time you get to the boss and would be using it. Sitting on abilities in order to "save" them is just limiting yourself. Even if you may not get full usage out of an ability, it's still better than no use out of an ability because you are "saving" it.
The only time you should be "saving" an ability is because the pack you are fighting is pretty much dead and you are making preparations for the next big pull.