Maybe this makes me a jerk, but I kind of don’t care to make it easier for people who aren’t willing to get there at opening. Definitely not in favour of over complicating the system to benefit people who weren’t willing to put the effort in to ride, putting people who were willing to work at a disadvantage.
What I see happening in practice, multiple parties missing out on the initial drop, waiting for the second and maybe missing that, possibly even missing the third. I see lots of people not truly enjoying their very expensive and for most people rare Disney day because they are preoccupied with trying to get on this one attraction. I see DHS crowds still being a mess because people held “hostage” trying all day to get their BG. It’s not a park like MK that has plenty of smaller attractions to eat crowds, or an area like World Showcase that encourages wandering.
If they wanted to stagger BG, I would so much rather they are preassigned windows given out in some way beforehand. Like a FP I guess

. I think your method makes for a very stressful day for those whose #1 goal is riding, benefiting people who may not have cared as much and just luck into a BG.