I intend to go to every festival as they feel like a key part of the game if you're playing it like an RPG lite, which I do. If you're not playing specifically to Min-Max or for something to grind (other than Friendship), then the Festivals are a featured part of the game immersion even after you have all the Rarecrows, paintings, or other goodies. Plus, the Night Market has the Deep Sea Fishing, which is my favorite event of the Stardew Valley year.
And you get to do it 3 times!
But of course CA giveth and CA taketh away. I noticed that my game doesn't seem to remind me that a Festival is starting any more and I've missed a couple recently, only noticing the following day or so. Now a true bastion of efficiency puts her horse blinders on in order to focus on the barely one thing that can be kept in mind at any given time, so it's possible I just missed the popup but its happened a couple of times now.
And of course you very well know that afterwards Abigail just casually parades around eating Omelettes, Fried Eggs, Chocolate Cake, Blueberry Tarts, and occasionally dropping an Egg, saying "oops!" I see right through that. No competition at the Egg Hunt and Ms. Fake Hair Color (yes, I said it!) acts like she owns the place again.
She doesn't even like Eggs.