the acres a grain drill can plant in an hour is based on several things.like how much the seebox holds.how much you are planting pre ac.an how often your having to stop an refill your seedbox.you should be able to plant 4acs an hr depending on what your planting.
Besides all of the settings and amounts, the biggest governing property is speed across the gorund. Took me 3 hours yesterday to drill 8 acres with a 10 foot JD/VanBrunt.
Just today I planted 20 acres of wheat/oats mix with a GP 10' no-till drill. Took right at 3 hours not counting filling the bin with seed. Relatively flat pasture so I could make a good pace. Took 1 hour to fertilize.