AGX, if you are doing hand inversion, or agitation, then many people will only agitate for 10 seconds +- every minute and that has been successful for about a century, give or take.
If you have been using a Jobo rotary processor as I have, then it does look a little low on the agitation, but whenever I hand develop, I do it at one minute intervals, doesn't seem to make much difference if you adjust your developing times accordingly.
Thanks for the link, very good.
Mick.