Painted deck

Last spring I built a small (6x12) covered deck, using 2x6 treated lumber. Then I made a couple of errors. After letting the wood dry for a month, I sprayed on a coat of Thompson's Water Seal. Probably not needed on treated lumber, but I did it. I let that dry for six or seven weeks, and then painted the deck with latex porch and deck enamel. It started coming up right away, and the bare spots increased until now, so I am taking off the old paint so I can do it over. I borrowed a small electric pressure washer (Karcher K 2.26 M) and began to attack the paint. The machine is stronger than I expected, and I have taken up a few splinters with it.

Some boards give up the paint easily, and it seems to have very little adhesion. About half the deck is tougher, to varying degrees, and in some areas I can't get the paint off at all.

Now my questions - having gone over the whole area, should I assume the remaining paint is now permanent and ready to repaint? Also, should I expect better results next time, with similar paint, or am I beating a dead horse? How much drying time until I should try to paint again? Any prep needed this time?

All help will be appreciated.