My assumption is that the first four batches will be much smaller than that. Together, I think they will account for less than 10% of the total shipments. They have individually-milled cases, and mechanical design iterations. The first two have PCB design iterations.
Hidden details: rampant speculation on batch sizes.
To me, it would make sense for Purism to order as few as possible of the first revision PCB. Judging by the recent pictures of the PCB, the first revision is panellised 2 per panel, so depending on the supplier they might have as few as 20 of those individual boards. I’d be surprised if Aspen is more than 100 phones.
Birch has another new PCB, so I think that will be a small batch too. It would be crazy to order 1000 new revision PCBs without first ordering a smaller batch to verify that they work correctly. Again, I’d expect closer to 100 than 1000.
They’ll also be refining the mechanical components; the case and the switch caps. Early revision PCBs can potentially be modded by hand to correct design errors, but if the outer cases of the phones turn up warped or with screw holes in the wrong place or something, then it might not be economical to modify them. An expensive error. So, they will definitely need to order small quantities of those sorts of things first.
Maybe the batch size of Chestnut and Dogwood will be based on small batches of mechanical components from a supplier? Or maybe they will be using them to ramp up their production processes and figure out how to assemble these phones efficiently in large quantities. It’s hard to guess. I don’t think they would just release two arbitrary batches of phones that aren’t driven by any particular requirement.
Edit: I assumed that the first two batches had PCB design iterations. It’s just occurred to me that this is not necessarily true. It could be that they are just different batches of assembled PCBs. I’m not in the mood to think it through again based on different assumptions.