A simple trick when one wants to recalculate a lot of phases, is to CTRL+Click on the phase icon in front of the phase name, and all phases that follow from this phase will be set to to be calculated:

In the example above, phase 4 and phase 5 are not modified, since these phases do not originate from phase 3, but from phase 2.

This trick also works if you want to disable such a phase tree branch (a phase with all its child-phases):

This feature is introduced in PLAXIS 3D2012