Just try it some, I assure you it does the job well. That sample line comes directly from D2SRoBa which has been consistently accurate to within 1 to 2%. It is extremely well tested and I never argue with that kind of success, it's way beyond my paygrade
Good point about the GOP 3/4. I should have mentioned that all the test results in the proof spreadsheet were based upon M=3 and N/M=4, which is all I ever use.