+xTo be fair not that much more.
Put a vernier on a piece of uncurred umaterial an that's the thickness you will get cured,be it 15psi or 90
Just loose a little bit on a ply stack with multiple layers as one layer fits into another
Don't really need 90psi,but your 100% it's in the corners
Even 30psi will give you 99% success
So, crucial for very high end stuff but not for the rest of us.