Looking at the wait times and how they change, I suspect the do "runs".
For example,
06/28 - 07/04: Black
07/05 - 07/11: Cherry
07/12 - 07/18: Beach
07/19 - 07/25: Maple
07/26 - 08/07: Black
So if you order a Black set today, (06/30) you're going to have to wait until he next run of Black speakers to get FOs... 4 Weeks. Maple is only 3.
I would further speculate they have difference production facilities wit dirrferent schedules, hence different wait times for different types of speakers with the same finishes.
I am completely making this up based on nothing more than looking at different wait times per finish and per speaker. I could be 110% wrong.
Thanks
snazzed