KNOWING WHEN TO PAUSE
Knowing When to Pause, How Long to Pause and When to Call a Session Done
Firstly, groundwork is the best place to learn how to develop great "timing and feel", which is what this question is really asking about. Pausing aligns with "timing" and waiting aligns with "feel".
Why you need to pause: You pause so that the horse can identify a release of pressure. So, they can connect that they did something that made you go quiet. If you don't pause the horse has zero clue that it did anything right. Also, you need to learn how to be quiet...most people struggle with this and don't recognise how much noise they create in their unconscious movements and nervous energy. In this photo we see Sarah Leagas demonstrating a pause with her horse in groundwork.
Therefore, you need to pause after every "release of pressure" to ensure the horse identifies the pressure has been removed.
How long do you pause for: Well, it depends...
In the early stages of training a response, pause for at least a breath (breathing is good to focus on as it keeps your thoughts present and paying attention to the NOW) or until you feel the horse's attention start to drift from you (see how focused Sarah's horse is on her). For big break through or improved responses from the horse, pause for at least 20 seconds.
Length of Training: Again, it depends...
For a particular response, I will train until I see improvement, then move on to another response. Never drill a horse doing a good response, moving on adds to the horse's sense of success in being able to respond correctly.
Length of training in general, I train for no more than 45 minutes including rests. Training fitness can be greater and built up over time.