2021 BRN Discussion, page-11318

1 layer per day is on the money. Here is an article from a few years back.

Battling Fab Cycle Times

"Generally, the most common metric for cycle time in the fab is “days per mask layer.” On average, a fab takes 1 to 1.5 days to process a layer. The best fabs are down to 0.8 days, Leachman said.

A 28nm device has 40 to 50 mask layers. In comparison, a 14nm/10nm device has 60 layers, with 7nm expected to jump to 80 to 85. 5nm could have 100 layers. So, using today’s lithographic techniques, the cycle times are increasing from roughly 40 days at 28nm, to 60 days at 14nm/10nm, to 80 to 85 days at 7nm. 5nm may extend to 100 days using today’s techniques, without extreme ultraviolet (EUV) lithography."