I'm sort of doing all you mention.
I drill under water with a nonskid surface underneath. I go slowly, applying just enough pressure (the dust swirls in the water) and the process eats up
at least one full battery charge. The latest hole took one charge for just the pilot hole and over 30 minutes (I stopped looking up at the clock). Spare battery died on the second larger hole. Waiting for the first battery to charge up now.
I drill sequential sizes so I don't take out larger chunks.
ETA: Some of the time and battery usage is because the bits are no longer efficient. Hence the need for better bits. I'm also wondering if I'm expecting too much from regular household powertools.
---------- Post added at 04:51 PM ---------- Previous post was at 04:11 PM ----------
Has anyone tried
this? I'm gonna go get it tomorrow.