I used MeshMachine mostly when i wanted to finalize or revert something. Not all the time.
Basically i used it when i was happy with all stuff made with HardOps + BoxCutter which are mostly modifier based. So after modifiers are applyed i do cleanup and there MeshMahine comes handy.
Sometimes cleaning up is not even needed though but that depends how complicated specific part gets.
Just by watching some of videos from masterzeon https://www.youtube.com/c/masterxeon1001/videos should help you understand most of HardOps+BoxCutter stuff.
Also Ponte seems to have good tutorial videos and tips https://www.youtube.com/c/PonteRyuurui/videos