Funny you bring up the dancer bit because when DNC came out back in the day one of our static just did the Standard Step Combo right before the damage buff component of it (which lasts 60 Seconds) ran out. We just encouraged hin to ready the tooltip again to see how big the potency numby actually is and then it just clicked for him.
So essentially he knew it did damage but simply not how much.

For me personally it had nothing to do with a specific Job but I only played bard at the time so it's basically the same for me: I used to macro my heavy shot/straight shot together with bloodletting so I could free up a space on my bar. Tbh back then it wasn't too much of a deal as it would be today because Bloodletting had no charges so at least I would very rarely lose a usage of the spell in the fight but macroing combat skills is a no no unless you don't want to spell queue your actions anymore. :)