Suppose I, a wizard, have a Pearl of Power attuned and have not used it today, and I have just finished a battle in which I used at least one spell slot of 3rd level or higher. I could save the pearl for later, only activating it when I know I really need that spell slot. However, the risk in doing so is that activating the pearl requires an action, so whatever spell I want to cast in the moment would be delayed by one round if I fail to anticipate the need. So, it seems that the correct choice is to activate the pearl as soon as I am no longer in danger and can afford to use my action to do so. However, perhaps I am missing something. Is there ever any benefit to saving the pearl for later, or is using it now always the better choice?
(You can assume that my sleep schedule is fairly normal, so “the next dawn”, when the pearl regains its daily use, roughly coincides with the end of my next long rest.)
Yes there is (at least one) reason
You are a wizard who has not yet used Arcane Recovery. The optimal interaction between a Pearl of Power and Arcane Recovery depends on your level, the number of slots you have expanded and when you anticipate having a short rest.
For example, an 8th level wizard who has cast a 4th level spell could regain a 4th level slot with Arcane Recovery or a 3rd level slot with the Pearl. The same wizard who has cast a 3rd and 1st level spell could recover both with Arcane Recovery or just the 3rd level with the Pearl.