I think that the biggest difference is between constant agitation and intermittent agitation. If you were using a rotating drum system (Jobo) with fast revolutions, then you would see a real difference.(posted 9377 days ago)Between agitation in 30 or 60 second intervals, I believe the biggest difference is in the shadow values. The high values will not be that strongly affected.
The best thing to do is burn some film, all of the frames being the same subject. A still life of egg, orange, grapefruit, and Kodak grey scale card against Kodak grey card is good. Have enough of the grey card showing in the scene so that it can be measured if need be (1/4-in. of film area). This way you will be able to judge what you are seeing, and obtain impirical results.
Remember: Film is cheap, the scene of your life isn't.