Another thing to think about is a quote that Parelli didn't invent, but uses regularly. This applies to any sport and most every hobby or...

Practice doesn't make perfect. Perfect practice makes perfect.

If you continually allow imprecision and lackadaisical responses, your horse's performance will reflect that. There is no one else to look to but the rider for this.

Then, when you really need precision, your horse has no concept of complying with you since you don't ask for it in a training situation.