IIRC, in the days of FP+ pre-booking fewer than 3 was definitely a valid strategy, since you had to use everything you pre-booked. With LL-MP only requiring you to use 1 and potentially allowing you to modify day-of, I will be interested to see if there is any difference strategy-wise between pre-booking fewer than 3 and pre-booking 3 regardless and just modifying day-of.
That goes to my current dilemma. I have a compulsion to start adjusting my plans for LL-MP, but there's too many unknown variables, so I can't properly plan yet and my brain is stuck in stressed limbo. I mean, I've only got less than a year to optimize my park days and strategy.