I'll never know why people think that practice makes perfect. It doesn't.
If you're trying to be a dancer, and you keep bending your knee when you kick, you're not going to magically keep your leg straight when it's time to perform.
When you do something over and over, it gets ingrained. Practice makes permanent, not perfect.
If you're trying to improve your writing, you have to do much, much more than just write everyday. You need feedback from real readers. You can learn more about improving your writing by checking out this article
You can practice writing 'til you're blue in the face!