To the players that would participate with a lockout to play with their friends / play with others.

Have a (practice) arena.
Rules:
You can start from any save point up to the point that the furthest progression member has unlocked in either practice or BCoB (this week). Practice does not count for BCoB progression.
There is NO loot / gil in practice
There is NO armor damage in practice
All turns are the exact same as they appear in BCoB (no reduced damage or other changes)
There is NO lockout for practice mode.
Practice mode has twice the event-time as normal BCoB runs (in the expectation that you would not finish in a regular run you are allowed more time to practice)
Practice mode will be available for dungeon search if not server-only duty finder.

This would allow players to go back and 'help' their friends learn the mechanics of all the fights, it would NOT increase the availability of any equipment. It would not cause a gil drain either.