When the USBC first announced that the patterns would be kept a secret I didn't like it but after bowling in the Open for the past two years and really following the tournament closely I think it's the right decision. I think it just gives the pros (and top amateurs) too much of an advantage. I think they would do much more with that info than us mere mortals that are competing with them in the regular division.
I think you can prepare for the tournament without bowling on the actual shot as well. I did so by bowling on the house shot and working on accuracy plus playing a few different lines for scenarios that I might run into. There's enough information on the internet about how the pattern plays as well so one can make educated equipment choices before going out there. I'm not sure I would have bowled any better if I had bowled on the actual shot.
Also the Bowlers Journal
is on the doubles and singles pattern so technically you can bowl on both patterns prior to bowling the Open since you can still set up a practice session on the team pattern.