It's what I'm doing, haha.
At the beginning I was more careful about using them, waiting to use them if I close to getting enough to run the next tier. Now? I'm just going all out. Obviously, I'll wait if it's within 1-2 stamina points, but if it's something like 5 I just use the stone anyway. It's times like this I wish Dokkan Battle had stamina overflow.
Edit: Also, how common is Namco Bandai removing "cheaters" from the post-event results, or is the final count before maintenance pretty constant?