It is often said that defensive skills are perishable. If you don't continue to maintain or improve those skills they diminish. Practice is the "rent" that is due to keep the skill at a high level of on demand proficiency. This mantra can certainly apply to more than defensive skills but if you're reading this you are probably more concerned with your defensive skill set than your observance of the niceties of society.
I recently worked with a shooter that I had trained three years ago. When I last saw them on the range, they were doing pretty well. I found out that they changed jobs a year later and hadn't done any firearms skill maintenance in the interim.
While working with them, I noticed that their ability to hit had held up reasonably well. What hadn't stayed with them was speed, manipulations, and malfunction clearance. I suspect that it is going to take them several weeks of dedicated practice to get anywhere close to what they had before. And when I say "dedicated practice" I mean daily dry fire, 4-6 times a week, on top of 1-2 range sessions a week. In other words, 40-60 hours of work, and I don't know that will get them 100%, but it might get them to 80% or that neighborhood.
There are several things that can get you firearms proficiency. Going to a class and learning is certainly one of those things, but it doesn't end there. If you take a class and then do no dry fire or any other shooting afterwards, you won't get the opportunity to really put those lessons into practice. While the class itself may have been fun and solid learning, the real rewards you get from a good class don't happen during the class, they happen later. Only when you put in the WORK!
I am advocating that you continue your training and put in the work to develop and maintain your skill. Justified Defensive Concepts would be honored if you came to train and work with us. We will respectfully challenge you, give you significant personal coaching during class and we'll give you a plan to maintain and/or improve your skills after the class. Like seeing a personal trainer, we'll give you a path toward improvement!
If you're serious about your firearms skills be sure to put in regular practice. Do the work! It has been asked before, "if you knew somebody was going to try to harm you tomorrow, how would you train today?"