I got the impression from both my store and from forums that the agitation scheme in the manual is way too fast and harsh. I was recommended to do it more slowly for one minute, then every 30 seconds
There are a significant number of people who use continuous agitation (in rotary processors) to develop their film. And they get great results.
There are even low or almost no agitation schemes ("stand" and "semi-stand") that some people have success with, although the potential problems introduced by them require some experience to deal with.
The purpose of agitation is to move exhausted chemicals from the surface of the film and replace them with fresh chemicals.
Any agitation scheme will work, providing that:
1) there is enough, sufficiently random agitation; and
2) it is repeatable.
With the exception of some of the specialized effects from the "stand" related techniques, and with the exception of some really specialized materials, varying the agitation scheme will mostly just increase or decrease contrast. You can counteract those increases and decreases by changing the development time.
The worst mistakes you can make with agitation are:
1) not enough agitation;
2) not random enough agitation (as in not having consistent effect across the entire film or films); and
3) inconsistent agitation, when comparing one developing session to the next.
The Kodak recommendation prevents all these problems, without significantly (or at all) increasing grain or having a deleterious affect on highlight density.
Millions (billions?) of rolls of film have been successfully developed over the decades using Kodak style agitation.
Similar high quality results can be obtained with the 10 seconds every minute approach.
Just don't switch back and forth between them.
FWIW, the style of agitation I've used (45+ years) since I stopped using the "see-saw through the tray in absolute darkness" approach I started with is closest to the Kodak approach.
Have fun!