The OP is proposing using a fixed number of agitations instead of a fixed time-interval.
My knowledge of chemistry is rudimentary, but this makes perfect sense to me.
If a chemical reaction only proceeds half as fast and thus takes twice as long, then doubling the time-interval (giving the same number of agitations) will produce the same result as double-speed and half-interval.
However, the rate of diffusion through gelatin does not depend on dev-rate, so that complicates things.
Anyway, I have created a concentrate giving XTOL-quality, and I designed it to have twice the dev-time as XTOL. And I recommend agitating every 60 seconds instead of Kodak's recommendation of every 30 seconds. It's worked fine in my experiments.