Originally Posted by
PAX62
Outside one of the few known flukes or risky tactics, for plain ol reservations the boarding positions are doled out in this order:
Business Select
A List Preferred Members
A List Members
EBCI Purchasers
THEN:
Everyone else that is left fighting for check in at the T-24 mark
So chances are slim to none that you will get a better check in at T-24 than you will with EBCI.
Only BS and T-24 checkins are dependent on chronological check in time...A, A+, and EBCI are pre assigned through WN's mystery algorithms.
Southwest reissues the positions of passengers who are checked in but then cancel or change their flight. This means that it's possible to check in manually and receive a better position than you would have if you had purchased EBCI. While unpredictable, this is less infrequent than you might think.
A-Listers are assigned positions via an unknown system (with + coming first), but EBCI positions are assigned based on the order purchased (with Anytime coming first).
That list should also mention Preboarders (a sometimes significant number of passengers) and Family Boarding (following group A, a sometimes significant number of passengers that often divides the EBCI group).