What we ended up doing was put 6 or 7 2.5D runs in a work day and then when we were somewhat confident we got it, run a full 3D at the end of the day and go home
Only once did it take another 3D run
We were running sim up to 30G, by the way and verifying IRL upto 20G
My ex colleague put the plots of everything on top of each other in a good structure and an intentionally bad one (smuggled that into the design for verification) and we were shocked how accurate the simulations were