There will come a day in which your training falls apart when you really need it.
Your dog blows off your recall to chase a skunk.
Your wonderful crate manners turns into pawing and howling and you come home to complaints from your neighbours.
You place your dog in an emergency downstay only to find them running across the field to join you.
All successful dog training requires maintenance. Without maintenance your dog training will break and it might break at a really inopportune time.
There are usually signs that your training is getting a bit rusty far before it breaks down. Warning signs might look like a slow recall, intermittent whining in the crate, and a downstay that seems to slowly creep forward over time.
This may be due to lack of practice or it may be due to using inconsistent criteria and expectations for your dog.
You may become a bit lax on your criteria over time. Occasionally you let your dog bolt out of the car to meet its friends, you don't interrupt overexcitement at the doorbell, or you accept a slow recall that sniffs all the flowers on the way back to you.
You also may start to let your training slide. Maintaining your training means regularly practicing and reinforcing known behaviours in a variety of environments with the appropriate level of distractions.
I regularly reward eye contact to ask for permission, a sit at the door to go outside, or a fantastic recall. Just because my dog is familiar with the exercise, doesn't mean they will continue to offer it over time without at least intermittent reinforcement. I am also consistent-if I asked for a stay, my dog needs to stay where I left them to receive their reward. By practicing regularly and keeping the same consistent expectations for my dog, I set them up for success by keeping their skills sharp and their understanding clear.
Behaviours we stop reinforcing- through toys, food, play, or access to something the dog wants- will weaken over time. Your training WILL break if you let it. Prevent that with regular practice, clear and consistent criteria, and strong reinforcers far before it gets to that point.