Mark, thank you for the explanation.
Sounds interesting, although I come from a rather different background with regards to agitation. For around 30 years I have developed all of my film in a Jobo processor, B&W E6 and C41, agitation is sort of in my blood, so to speak.
Since it became available, the SP-445 tank has surprised me so much and I have taken to it like a duck to water. I was part of the kickstarter project and since receiving my SP-445 tank and trying it for 10cm x 13cm (4x5"), I have used it exclusively for that format since; it works very well. I find I get virtually identical processing results compared to the Jobo using the intermittent agitation in my SP-445. Constant agitation for the first 30 seconds, then 10 seconds every 30 seconds. I came to this conclusion as according to the flow patterns obtained by the inventor of the SP-445, effective movement of liquid ceases 20 seconds after the last inversion.
With deep tank processing, as in Dip "N" Dunk systems, you almost immediately know if the Nitrogen bursts at 10 second intervals have stopped. The damage to E6 is usually irreparable, C41 is mostly recoverable; agitation is really a big difference.
I have often wondered about pyrogallol and pyrocatechin developing agents, your reply pushed me to catching up with what they do and how, so I consulted my book, "Developing" by Jacobson and Jacobson, eighteenth edition revised July 1976, 1980 reprint; pages 215 to 222.
As I don't have either developing agent, I will forego any experimentation, but one day I may just get some for a try.
Footnote: As I was just reading the book, which is about film developing, I thought it amusing that it was printed in Bath, England.