"To sand half a hood took me over an hour to do with a sanding block."

I've been using 600 grit for wetsanding my test panel ('88 Monte Carlo SS trunk lid) and it does take me a good hour and some change to just do that, plus whatever additional time after the first pass dries enough to see what I missed.

So don't worry, you're not alone in by any means in that department. But it certainly makes the next coat go on smooth as a babies... well there isn't as much orange peel to sand down at any rate when the orange peel from the previous coat was good and taken care of.