I think any conversation about healer DPS is working off the obvious unstated assumption that your healer duties are being performed sufficiently. But I think setting a goal is a good idea. If you can clear the fight with 0 DPS - and you say to yourself "ok now I want to clear it with 100 DPS" if you achieve the goal, you know you are improving - as everyone alive with 100 is better than everyone alive with 0. Attempting, versus not attempting, helps you become a better player as you are forced to become more shrewd with GCD and MP usage in order to accomplish the goal.

But another thing to keep in mind is the value in healer DPS sometimes doesn't show in the final number, but moreso in pushing phases and skipping mechanics. For instance when we started doing T12, I would do great dps in the first phase, but then would barely do any dps after. So while I might end the fight only 60 or 70, my DPS in the first phase helped skip a mechanic and get us 1 less Bennu to deal with.