Your analogue is probably true to a certain extent, but in reality maintaining your current form in any domain of expertise is easier than achieving that form in the first place.
I only really have video games as an easily quantifiable example, but playing in top 1% of League of Legends doesn't really require anything more than a couple games a week to maintain that level. I have the knowledge, I know what to do, and I can execute on that. Perhaps this would be harder in a domain that leans more on physical or mental condition which tend to decrease over time, but probably not so much in Chess and the like.
I only really have video games as an easily quantifiable example, but playing in top 1% of League of Legends doesn't really require anything more than a couple games a week to maintain that level. I have the knowledge, I know what to do, and I can execute on that. Perhaps this would be harder in a domain that leans more on physical or mental condition which tend to decrease over time, but probably not so much in Chess and the like.