That's awesome. Two thumbs up for Aydan from The Rob.

Group size will naturally increase as the distance to the target increases. This is due to slight errors in aiming, release, or form being magnified with the increased distance. The mental aspect of knowing you're shooting at a greater distance can cause a shooter to "try harder" which rarely produces good results. Shoot it the same way no matter the distance.

I would not advise increasing the draw weight. Increasing the arrow speed would help if in an unknown distance event to help with distance estimation errors, but since Aydan is shooting in a known distance event I don't see where increased arrow speed would be an advantage.

I'd suggest to keep focusing on the form and techniques George showed y'all. Time is the best teacher, by that I mean it will take 3,000 to 5,000 perfectly executed shots before the body and mind will accept it and the shot will be automatic ie the "zero mind" zen stuff. If I remember right, Aydan shoots at 10 and 15 meters. Have him shot at 20 meters a couple of times. This will make 15 meters seem easy.

As for fatigue, with practice the endurance will come. Practice up to the point where Aydan's form is still sound and he isn't shaking. Once he reaches that point, stop for the day or take an hour or two break to let him recover before continuing. Practicing beyond the point of form break will cause the body and mind to not replicate the perfect shot and introduce variances to the shot process. Perfect shots come from perfect practice whether it 100 shots or 1 shot. 1 perfectly executed shot will do more good in the long run than 100 less than perfect shots.

Basically, just keep doing what y'all are doing and have fun doing it.