Reincarnation of Another World Sage - Chapter 18.1

…if he was almost out of magic power after flying to the tree in the first place, and then headed back to town, and used up more power dealing with the “escort adventurers”, and then flew back…
How does he still have this much power?
I must be missing a lot of time skips.
This is going to be like finding out that different speech bubble borders meant non-verbal communication, isn’t it? Really obvious in retrospect, super confusing until I figured out the obvious….