DODGY !!
The procedure is risky.
It fully relies on see-and-avoid with all its limitations.
To further compound the problem there is very high density traffic as nobody keeps to their slot times, no use of radio until #1 on final, and no ATC being present.
It is only by sheer luck so far in the big sky that nobody has had a collision.
Which is why I stopped going to the PFA rally by air. Too many times, I was cut up on downwind or even final by people who clearly had not looked at any instructions and often heard people calling up for landing instructions on the radio.
A conscientious pilot can read the instructions as much as he likes and keep the best possible look-out but the high-density of idiots around fly-ins like Aeroexpo means that a mid-aid is just a matter of time.