Here's what Richard J. Henry says in the second edition of his CONTROLS IN BLACK AND WHITE PHOTOGRAPHY (page 214): "Since the edge effects occur because of lateral diffusion in the emulsion layer, the degree of agitation should have no effect on them and Barrows and Wolfe stated that agitation produced relatively little effect. Schwalberg disagrees, stating that violent agitation will completely eliminate these edge effects. I cannot agree since identical results were obtained on my machine mixer with very vigorous agitation, and inversion of the tank at 1-min intervals, and at 20 sec intervals."(posted 8758 days ago)I have an old article on Rodinal by Bob Schwalberg in which he recommends reducing agitation for greater acutance, but Henry's testing procedures were pretty solid so I suspect he's right. I believe he did most of his tests with D-76 and HC-110.