Paint Stripping with a DA

I had intended to strip the paint on my project with a pneumatic DA sander. I started last night on the deck lid. Using 80-grit, I spent about 2-1/2 hours working on it and didn't even get half of the top surface done. There are two coats of paint and an over layer of primer (origin unknown). Is this normal for how long the process takes? Do I dare go to 30 or 60 grit to get closer to bare metal and then go to a finer grit? I really thought that I would be able to buzz through this quicker than what I found last night! :munky2: Thanks. L8r

Jim