One of Richard Pryor's classic characters, Mudbone, had a line that went something like: "Somebody ask me, well, Mudbone when's the last time you got some? I told 'em, 'Yesterday.' Cause that's as far back as I want to have to remember it."
I feel the same way about training jiu-jitsu. Maybe my answer to "when's the last time you trained?" will never consistently be "yesterday." But if there are 365 days in a year, then training at least 15 times a month, at least 180 times a year, means you're on the mat virtually every other day. And over the course of a year, year after year, that's a pretty mean pace.