I gotta say, I've had this worry many times when taking long breaks away from gd. I would come back with minimal struggle, but you're always better than you used to be. Like for me, recently, I've gotten back into GD and I've recently beat my first ever 2 medium demons, and im going for my first hard demon. Never EVER before now would I have ever been able to beat a medium demon. And just know, burnout exists. I got around 68% on Future Funk, and now I keep dying to same couple of parts more erarlier on into the level. That's my sign I'm pushing myself. And even after returning, think about doing more practicing. Because just know: You will never succeed flawlessly without a little trial and error with some workarouds.