Should I just focus on the ML?

If I'm really good in master league but stink in the Ultra and great, should I just focus on master league?

I've been playing for a little under a year now and really enjoy PVP. I have earned myself 3 Ace badges since June of 2025. 1 in the Master Premier, 1 in the mega master, and another in open master.

I currently run 3 teams of 6 that I use interchangeably for each league, and I have been told that if I struggle with my teams in great and ultra, it's a skill issue. In open great league, I have no problem functioning in the 1700 to 2100 range, but the moment I cross that barrier I go from winning 4/5 - 5/5 to 1 or none. Same story in the Ultra. But in master I have no problem getting to the 2,200 range and just under 2,300 amd I'm sure I could climb even higher. But that's usually when the week ends and I have to play in a different league, and my ranking plummets.

Should I just abandon the Ultra and Great and only play when the master cups are available? Or continue on and attempt to learn something new?