So, of course, you can rush through the entire map with a dozen small fairies in a week!
The fact that Deemer showed inadequate behavior in this tournament doesn't mean that the battle couldn't be won if he had played differently. Deemer is the same for everyone, and anyone can achieve such a result. The main thing is to carefully plan the entire playthrough.
I can upload my battle with Deemer. There, he doesn't sit in the castle but goes on the attack!