Probably more than you'd think. But airlines don't cancel flights in situations like this only for safety. It's also to prevent planes from getting stuck there and messing up the rest of their network.
I was getting 1.5" per hour rates in the afternoon round of storms. Just a hair south was probably getting double that and a recently repaired stretch of road that got washed out in June got washed out again
I flew in last night and spent about an hour in a hold pattern waiting for storms to clear to land.
Then got soaked walking across the parking lot to our car.
Just .25"/.5" hail here. Though enough to clog gutters and making my yard a river again. I was eyeing that cell though willing it die out, which it did.