For 楷書 type fonts this may be true, but you ought to know there’s more to it, don’t you?
1 GPU - 30 GB/s TX - 12 seconds
2 GPUs - 60 GB/s TX - 6 seconds
4 GPUs - 120 GB/s TX - 3 seconds
Then you just optimize your batch size to match the compute time to the upload time of each GPU. The expert calculation results can be retrieved from the GPUs and summed up.