Mike, the times you cite are for E6 and the discussion at hand is about C41.
PE
Yes I know. The point I, poorly, was trying to make, was, follow the manufacturer instructions.
There's a old reference sheet, on Jobousa website, regarding E6 1st development times. It says 6'30", Except, Fujichrome, which was recommended 7'30". Rather than following Tetenal's, Fuji's, and Kodak's (old instructions for 5 liter kits), I used the longer time and I had over developed slides. I used auto bracketing so no tragedy .
For C-41 Kodak has clear instructions for rotary development, the times are the same. Kodak does say don't replenish with rotary. Clear, no add 15% this or that .
For black and white, for XTOL, which is what I use there is clear cut straight forward instructions.