More agitation leads to more development. Shadow areas will only develop so far, but highlights will continue to develop, causing an increase in overall contrast. I don't think subtle changes make much difference. For example, I use inversion agitation with the MOD54. I use the timer on the Massive Dev App. The agitation is set to 10secs/minute. I can invert the tank 3 times, or 4 during that time period. I don't think it makes any difference. If, however, I decided to agitate for 30 secs/minute, or continually throughout the development time, I would expect that to lead to increased density in the highlights, and an increase in overall contrast. Some books suggest constant agitation for the first minute, or 30 secs. I follow that advice, and agitate all films, LF or smaller, for the first minute.
Alex
