Once your dog knows a behavior well, and can perform it in many locations and with many distractions, you can fade the use of your marker signal and rewards. In other words, you don't need to click and treat every time your dog sits for you. However, it's also important to pay off every now and then to keep your dog in the game and gambling. "This time might be the time the reward happens, so I'm going to keep doing what I'm doing, just in case."
Here's an example of how you can fade the use of treats when using a verbal marker while teaching a behavior like "sit":
Reducing the use of food rewards should be a goal, but always be ready to go back to using more or better treats when you add more distractions, duration, or distance to a behavior - at least until your dog has a clear understanding that this is the same training as before, just in different context. If a well-trained behavior falls apart when you go out into the world, that's information for you. It's time to help your dog by going back to food - usually a high value reward.
Once your dog demonstrates that he can stay focused on the task at hand, you can switch to a lower value food as long as you maintain the successes you achieved with the high-value food in that same location or with the same distractions.
Once you have decided to use fewer treats, bear in mind that never using treats again would be like asking yourself to give up ice cream, cake, or other goodies. There is nothing wrong with using food to reward your dog, just use it to your advantage - to help him get better with his skills. Sometimes it is fun to give your dog a treat, just like it is fun for us to get unexpected rewards. Also, if your dog does something really amazing that you would like repeated, then food is the best paycheck you can give him to keep him in your employment.
About the Author
Debbie Lewis, MS
I educate and support people as they deepen their understanding of their pet's behavior to create happy, healthy pet-people relationships.