Training sessions are always best in short increments of time, usually at approximately 2 to 3 inutes. However, with marker training, these sessions can be a lot longer. This will depend on the dog and its motivation level as well as how difficult it that you're trying to train.
Training is fun for your dog when the reward is high enough in value and your dog isn't tired. You need to make sure he still has the proper energy to get the training down. You'll have to watch his concentration levels. Too much training will take the fun out of it so keep your eyes peeled for any signs of tiredness or lack of concentration.
Every dog has a different level of concentration. Dogs who gain drive will also gain concentration. If you're just starting out training, I suggest starting out with just 20 treats in your treat bag. Once all of those treats are gone during the training session, then you're done. It is always better to finish a session with your dog wanting more.
Sometimes, new trainers will get really excited about their training session that they'll forget when they need to stop. This is why having a limited amount of treats in your bag will help. An empty bait bag will signal that you need to stop. As you continue to train, you'll start to get the hang of it and this will no longer be an issue for you.
In general, you always want to end a training session on a positive note. Don't make your dog too tired.
During the training, there will be times when a reward needs to be delivered at a specific spot (such as in the hand touch). There are also going to be times when the delivery of the reward needs to be turned into a "mini-event" as my good dog trainer friend Michael Ellis would call it.
Mastering marker training doesn't simply mean knowing the timing of the reward but also knowing where and how to deliver that award. New trainers will many times underestimate the importance of delivery and placement. They don't know that the correct placement of a reward can result in new behaviors being learned very quickly.
Let me explain the importance of reward placement with the following example:
When you are first training the "hand touch" exercise, you will need to mark the dog whenever he looks at the hand you want him to touch. The correct place to reward the dog is "at the hand the dog looked at."
Basically, you don't simply give the dog a food reward. You place the reward on the hand the dog just looked at. If the dog puts his nose on the hand, then you mark that touch then put the food treat in that very same hand.
Your dog will quickly understand that there is a relationship between his behavior and the reward.
This is called proper placement of the reward. When you reward at the correct "place", the learning process is accelerated.
Another example of proper reward placement is seen when training the place command. If you want to teach your dog to go lie on his rug or touch his touch pad, the first steps of the learning phase is by marking the dog simply looking at the touch pad. The correct placement after the mark is the reward being put on the rug or touch pad.
If you are working on an exercise like engagement, the correct placement of the reward after the dog is marked could be to toss the food reward on the ground and make the dog chase it like he would chase a ball. It could be to the mark or the point of focus. Pivot your body and make the dog chase the food hand around you (basically, move his feet) to get the reward. Adding movement to the placement of the reward will build drive.