I have always found Kodak's recommendations for agitation too aggressive, more to do with a commercial darkroom than the care and attention you can take at home. If you agitate aggressively you need short periods between agitation because of the possibility of air bubbles forming if the developer foams. So it is a crude means of avoiding the effects of air bubbles and not of avoiding the air bubbles themselves. Kodak wrote the recommendations to be idiot proof which makes sense.

I base all my agitation around thirty seconds initial agitation then three inversions on the minute followed by a swirl as the developer drains back into the Paterson tank. The swirl is instead of a tap on the bench. Variations are made depending on the developer, but I would never go to agitating every thirty seconds which I feel is too close a risk with most films and developers for blowing the highlights.

Steve