But why would they need to? 36 gates would hypothetically give them nearly 300 flights with 8 turns a day. They were not fully utilizing the gates pre covid and they certainly aren’t now. How much big do they need to be at BWI? Answer: not much. They could easily consolidate down to A/B and focus growth elsewhere, such as BNA, DEN, PHX, etc.
WN might be able to operate as many as 400 daily departures out of BWI with 36 gates at 11.1 turns per gate per day since the 18 gates used by WN and DL at DAL had an average of 11.1 turns per gate per day prior to the COVID-19 pandemic with 200 daily departures (195 on WN and 5 on DL) out of the 18 gates used by WN and DL at DAL.
WN is also less constrained at BWI than at DAL with
(a) WN not having to share its gates with other airlines at BWI, whereas WN has to share a gate with DL at DAL,
(b) WN being able to flights out of BWI that depart before 6:00 AM Eastern Time, whereas WN doesn't have any flights that depart out of DAL before 6:00 AM Central Time, and
(c) WN being able to operate flights to BWI that arrive at BWI after 12:00 AM Eastern Time, whereas WN doesn't have any flights that are scheduled to arrive at DAL after 12:00 AM.
WN is unlikely to be maxed out at BWI anytime soon with WN currently scheduled to operate 206 daily departures later this year (according to the WN fact sheet), even though I probably would expect WN to continue to make some cuts at BWI until demand recovers.
I also would probably expect WN to further expand at IAD if WN ever comes close to being maxed out at BWI.