Once the parts are available (frame, fork, rear frame, components...) assembling the bikes is mainly done by hand and the amount of bikes assembled per day or week or month depend of the amount of people working on the assembly. Once the bikes are assembled, testing them is also manual work, testing more assembled bikes before shipping them, requires more people.

These people are different people than the one building the frames.

To speed up assembly, Peter must set up an assembly chain (search for video of the Brompton factory to see how it s done for a factory producing about 50K bike per year), does such a chain already exist ?

The Vellobike+ KS project had the same problem and could never reach the initially announced production rate (that was smaller than what Helix would need to deliver all bikes in a reasonable amount of tine). Shipment of Vellobike+ started about one year ago and all bikes aren't shipped yet.

For the assembly, I think that Helix also requires more effort/time than a normal bike (examples: the lefty folding fork will take much more work/time to be assembled and mounted on the frame than a normal fork, the rear frame with its complex locking needs also more work/time, same for the folding stem...).