In this club-heavy district (specifically Westchester-Fairfield of the larger Met section), the M/Gs are all over the map...1 day, 2-days, 3-days, from early June to late September...
They almost have to be so spread out, b/c if even 1/3rd of these 60 clubs had it in mid-late September (as premium weather would indeed indicate) then they would start to shut out each other... and that's if we limit it to West-Fair, never mind the larger (130 more clubs) of Met section which includes LI and NJ...
Thirty years ago, it was a little bit different...there weren't as many "multi-day" M/Gs, and the 1-days were run in the middle of the week where they would least disturb member play...also the clubs' cultural identity was sharper (Gentile, Jewish, Mixed) and so the clubs tended to coordinate their M/Gs along those lines, whereas now those lines mean next to nothing...