And I didn't have this experience. Our arrival day is Saturday August 23. Our first MK day is August 24. My window opened at 1AM as well; I could not book us as a group (of three) for A&E for the 24th. I broke us up and found overlapping times for (around) 4PM. Checking back pretty regularly I moved us up (one at a time, always keeping either my wife's or my time overlapping w/ my daughter's) to about 1PM. I found individual spots open until about 45 days out.
Our last day at MK is Friday August 29th. Before I went back and booked for the 24th, I was able to get FP+s as a group for A&E that day for 1:20PM, with lots of choices. And that was as a group of three, not even booking individually.
And I was also able to book 7DMT as a group either day with, again, lots of times to choose from. That's why I'm surprised at the lack of availability in late September. I would have no idea why Disney would reduce the number of slots, either, as capacity is capacity, unless for some reason they want more people using the Standby. Another M&G (i.e. Epcot) should play no role in this.