I don't know exactly how any other test prep company's algorithm was written, of course, but I can tell you that you will be getting a lot more than 5 questions per section wrong on the real test (with the possible exception of an 800 scorer).
Also, I was interested to read a comment above about the dearth of geometry on GMAT Focus. A couple of students who've taken the official test in the past couple of weeks have told me they had very little geometry on the official test (2-3 questions). Wonder if that's a coincidence or a trend...