Have you ever learned something on piano but found that you couldn't play it the next day? Frustrating, right?
That moment when we learn something new is so special, so wonderful, that it can be a real letdown when we can't replicate it again right away. We work hard at practicing a new piece of written music, or learning to improvise over a challenging chord progression and it's a great feeling of accomplishment. "Yes, I am getting better!"
So it's understandable that we're disappointed if it doesn't "stick" right away. We try it again the next day and find that our fingers stumble, or we forget how it goes, or whatever. It doesn't seem "fair!"
A healthier attitude is to just accept that this is the way things go. It's all part of the process. Learning something new isn't linear like the way we want it to be. Once I accepted this for myself, I started to enjoy practicing piano a lot more.
The good news is that if you can't play your piece perfectly the next day, it will come back easier than before. And you'll know it better. You can also use this moment as an opportunity to study a different aspect of the music. Perhaps you focused on finger technique the first time around. Now you can identify the chords the notes are outlining. The piece will make more sense to you and you'll retain it better in the long run. Or maybe you primarily practiced the hands separately. Use this as an opportunity to slow the tempo down and play the hands together more. Again, it will "sink in" better now.
The main thing is not to get discouraged if your initial accomplishment doesn't "stick." Sometimes the "ups and downs" of play a piece are a necessary part of the learning process. One thing is for sure: they're unavoidable. The more you embrace this fact and don't run away from it, the better pianist you'll become.
You may also enjoy The Spirit of Play
Take your left hand playing to a new level with my free ebook: Left Hand Techniques for Jazz Piano
You'll also get my weekly jazz newsletter with practice tips and inspiration