FWIW, I know that with constant dosing 24/7, my tank has a daily alk swing of 0.2-0.3 dKH that lags behind the photoperiod by about two hours. It basically swings from a high of around two hours after "lights on" to a low of about two hours after "lights out" (due to consumption), then swings back up all night (due to dosing when consumption is basically zero). I changed my dosing schedule to dose twice the rate as the 24/7 rate, but only during the period starting two hours after "lights on" until two hours after "lights off", and my alk readings leveled out quite nicely. Not perfectly flat, but just about.
This is pretty much exactly my observations in my system. I may give your dosing tweak a shot. I've definitely noticed accelerated growth since things have become more stable in my system thanks to the alk monitor providing me more information than I previously had.