I took gordon's workshop. We did agitations every 45 seconds for 5 seconds. I also do the spend developer thing at the end. I put the film back into the spent developer for 2 more minutes after the fix. I do the initial agitation for 20 secons, then 5 seconds every 45 seconds until the 2 minutes are up. then dump the developer and into the rinse water with the reels. Since i use the jobo sheet film hand tank, and or the Nikor sheet film tank, I follow the same exact procedures for roll film with my sheet film (4x5) I have no problems with it. As for times, I get them either from the unblinking eye site, Or I take them from Gordon's book for the films he lists.