At the end it's whatever that works best, but as a starting/reference point, which of the following two agitation methods is considered "standard"?
From Ilford's Information Leaflet "Processing Your First Black&White Film"; this seems to be the same as MDC's guide
From Kodak XTOL datasheet
From Ilford's Information Leaflet "Processing Your First Black&White Film"; this seems to be the same as MDC's guide
Fit the sealing cap and turn the tank upside down
four times during the first 10 seconds and again
for 10 seconds (that is, four inversions) at the start
of every further minute to agitate the developer.
Each time you invert the tank tap it on the bench to
[IMGW][/IMGW]dislodge any air bubbles which may have formed
on the film.
From Kodak XTOL datasheet
4. Provide initial agitation of up to 5 cycles, depending on
your results. For KODAK PROFESSIONAL T-MAX
Films, provide initial agitation of 5 to 7 cycles in
5 seconds. For an invertible tank, one cycle consists of
rotating the tank upside down and then back to the
upright position.
........
5. Let the tank sit for the remainder of the first
30 seconds.
6. After the first 30 seconds, agitate for 5 seconds at
30-second intervals. Agitation should consist of 2 to
5 cycles, depending on the contrast you need and the
type of tank.