Am I missing something about recovery rate on flasks?

It seems unredeemable how bad recovery rate on flasks is. For an ultimate life flask, the max increased amount recovered is 80% and max recovery rate is 70%...So a flask that heals 920 over 3 seconds can heal:
1656 over 3 seconds (552/s)
or
920 over 1.8 seconds (511/s)
or
1840 over 3.0 seconds (613/s) at the cost of mana

The rate of life recovery is a mind-boggingly bad affix. I understand some affixes have to be more desirable than others, but as far as I can tell, it's worse than amount recovered in every single situation. Am I missing something?