I used 3/10 of 1% for my projections 20 years ago. I have one WW Razor and 2 SS bays. I serve about 20,000 with 2 competing iba's and 2 competing ss bays.
That projection was a little high for me. DTC x .003, but my wash is on a B- location; 40 mph where customers go 50+ . Location and egress...