When you forget skills or knowledge you once used but then neglected, I’ve noticed that they don’t fade away gradually. Some of the physics or math I used to use and know well stayed with me for years, and then, after several years or a decade of neglect, faded quite suddenly. Similarly, if you don’t run regularly for a while, but only occasionally, nothing about your speed changes until, one day, several weeks or a month later, there’s a precipitous drop or an injury.
My sense it that these tails aren’t exponential or even power. They’re step functions, leaps and bounds.