As someone who mains AST and WHM, I cringe every time someone casts regen spells before a pull. The good and decent tanks normally can keep it under control, but when followed up immediately by CURE/BENEFIC II OVERHEALING SPAM things kinda go down the drain.

And I really hate it when I'm on my alt (59 PLD, 54 DRK), I've clicked the regens off and had the healer complain "Why did you remove the regen!?" Because I don't need it right now! Use it after I pull so all ticks will heal!

Then I get called an idiot and bad tank for not wanting regens up before pull. Yup.