Pulverize spirit issues - am I missing something?

Im using this build from nikowrex:

https://mobalytics.gg/diablo-4/profile/fc4ba6b5-0827-4d56-9ae8-e5db7134c3bb/builds/0667adcf-346c-4ebc-ad26-de0bd5f93aca?coreTab=assigned-skills&equipmentTab=gear-stats&variantTab=1

When I was on the Pulverize tab, spirit never flinched and I could spam pulverize nonstop. I kept the Pulverize tab skill tree at first and added the Mid-game paragon board and gear. Don’t have all the GA hits and one or two wrong tempers, but could still spam. Spirit didn’t move.

Swapping to the Mid-game tab skill tree I now have spirit issues and I can’t figure it out. I run out after several quick slams and I have to let it recover. Especially during bosses. Can’t figure out what I’m missing. Is there a better build to use to let me spam? Better to go back to his base tab? I miss my spam-a-lot, but want to progress.

If it matters, I have an Heir, but haven’t implemented that yet as I have no other mythics.