What are the Pros/Cons of using an OTP vs a masked chip?
OTP also usually allows you to buy a programmer and program them yourselves, reducing that 30 day lead time further - to nil, if you keep unprogrammed parts in stock.

This allows you to trade the extra device cost against:


reduced inventory costs
faster time to market - delayed sales can be lost sales.
flexibility to deal with unsteady sales


And for steady sales of bulk product you can still reap the benefit of cheaper mask product.