Depends on your magic. I’m a Moonlight user so it’s actually better to have lower Explosion Size & Blast Size. Light is already like the worst at clashing, and lower the size makes the damage higher, I believe. So, if it benefits your magic’s pros, then do it to maximize that benefit.
(magma main) i have two spells created, one which is lowest size, explosion and one which is 70% on both. i recommend doing the same, regardless of the magic. i only use the lowest size spell when im 100% certain that it will hit, while i use the regular sized spell for when im only half certain of if it will hit or not