If I want to use less agitation to keep the highlights from blocking, I will have to develop longer, otherwise the shadow area will be less dense than when it was developed with normal agitation.

But if I develop longer, the highlights will get more dense also....

I think the main problem is the combination of them. The first (less agitation) is the solution but the second (longer) ruins your highlights again.

So eventually you will gain some, but is this worth the efford?
How much difference is there between the good and the bad.

Or do we add another variable, dilution. Higher dilution so that the highlight does not get enough fresh developer while the shadow is still working.
But this can result in streaking with stand development. Maybe first develop in low dilution, andd next in high. Or develop normally and after that put water in the tank so that the developer in the neg is still working until it is used up which would result in the shadow from working longer....
Wehave so many variables which can be changed and are interacting with each other, that it is complicated to finetune.