People often question how long they should practice a certain behavior before beginning to teach the next skill. Or when they can start upping the levels of distraction to proof a behavior.
It would be nice to have the perfect recipe to follow, but unfortunately, there is no concrete answer. THE SPEED AT WHICH YOU CAN PROGRESS IS DETERMINED BY THE DOG.
It is important to do enough repetition so the dog grasps the concept. But it is equally important to add criteria as the dog progresses in order to avoid hitting a plateau. If you spend too much time repeating the same thing over and over, not only will the dog get bored, but they tend to have a harder time moving forward when you up the anti.
As a simple example, let's look at the "Sit" behavior.
You first teach the behavior. You practice enough repetitions so that the dog understands that the desired response is to put their butt on the ground while keeping the front legs straight. However, if you fail to wean off the lure, modeling, leash assistance or spacial pressure techniques you are using to help the dog learn the skill, the dog may never achieve comprehension to the point of knowing the verbal cue alone.
You've unintentionally done too many reps without changing the criteria to achieve reward.
How quickly you can change criteria depends on the dog. So adjust your pace of training to the dog in front of you. Your new dog may learn slower or faster than your last one. It is the dog you are training NOW that you focus on and adjust to.