There shouldn't be anything you can adjust mid fight. Oo
Adjusting and increasing the output would mean that you deliberately held back up to that point or that you were asleep at the wheel.
In these games, playing as a DPS is pretty much 1 do it correctly or 0 do it incorrectly.
I get personal record breaking etc but it is my experience that every glance I take at the DPS numbers mid fight is taking focus off potential fatal mechanics or what I am actually doing. That's why I prefer do analyze data after the fact, when I have time to take a closer look at my performance (Only do that with mythic/Savage fights).
Maybe you are better than me when it comes to not getting distracted. I'm not the youngest kitten on the block, so I prefer to limit the information displayed down to the necessary bits.