One of the many things I brought with me from flying, despite years since piloting a plane, is an intense appreciation for regular, frequent practice, and variety in situations. I could not afford to fly often enough anymore to be safe, so I simply don’t. I had the luxury of flying every single day, usually with multiple students, across all phases of flying. I’d stack my skills against almost any pilot (as would most any instructor pilot in that type of setting), simply because of the daily practice, practice, practice. One can’t get good at something and then put it on the shelf until it’s needed again some day – it simply will not be the same.
Once while still a student I got word that our old ROTC commander from college would be visiting our base. He was an accomplished WWII pilot who’d also flown the Berlin Airlift. He was long since retired by the time he visited, and I got the opportunity to show him around because of my old association with him in college. He could not wait to try his hand at the old “Link Trainer.” He crashed, time after time after time. Yet he’d flown in horrible instrument conditions during WWII 25 years earlier. It was a very humbling experience for a very proud man, sadly.
Nothing has changed for the rest of us – use it frequently, or lose it. “Head knowledge” doesn’t count in an emergency, nor does old experience. Practice, practice, practice, and more practice, as long as you live – and regularly, and frequently, whether you THINK you need it or not. That way you keep up with where you are now at minimum. Again: use it or lose it.