Whippits gives you +5 defense but you miss out on the casting turn..so let’s say using them results in you getting hit for 15 (instead of 20) Then you have 3 turns where you get hit for ~15 now. Over the course of these 4 turns, that totals 60 damage with and 3 attacks vs 80 without and 4 attacks. You lose an attack turn but save a bit of damage. The only time I can think of where giving up an attack turn will be beneficial to you, for such a small amount of HP protection, is when you’re trying to recharge your strongest attack and it has a high refresh. Otherwise you’re just spending money to delay the battle.