My sequence with TMY is an initial 30 seconds of continuous agitation, followed by a 5 seconds every 30 seconds. And when I agitate, I hold the tank with my thumb on the bottom of the tank and my other fingers on the top - I have had tank tops come off while developing film, so I've learned to hold the tank so that can't happen. And to agitate, I flip my wrist so that the tank is completely inverted. I make this a snapping motion, so that in addition to agitation, the tank is also jarred a bit to dislodge any bubbles that might have formed on any internal surfaces. I did this in a teaching darkroom a few years ago, and the instructor went crazy because he thought that it would be too vigorous. Then he saw my negatives and understood that while it may be a slightly different way of doing things, it does work very well for me.
For 4x5 sheets, I use a slosher in HC110 dilution H. Again, I agitate continuously for 30 seconds, and then 5 seconds out of every thirty thereafter. To agitate, I rock the slosher insert inside the tray. The limit is that I don't want to rock the slosher so much that I splash developer out of the tray. I suspect that this is less vigorous than the case with roll film.