Yeah, only about 100% of the time. Go out and hand measure the roof while marking your hand measurements on your sketch report. Assuming they’re they same, send to insurance company. I’m sure their waste calculations are wrong as well. And I’ll bet they left on numerous items that need to be supplemented.
If they still refuse, order the exact amount total of field shingles, cap and starter as specified on the scope of loss. Not a bundle more. Call the IC a couple of hours before you finish to let them know (assuming you are going to be short) you are going to be short on materials and need written authorization to continue. If they don’t give it, tarp what’s left and leave the job until you get authorization. Get the HO involved. This approach works, we have done it often when we meet this kind of stupid resistance.