Each date in a series is a session. You can fine-tune sessions individually, including custom times and sessions that run past midnight.
Override a session to give it a custom time. Custom sessions won't change when you update the pattern.
Use Time slots per day to create more than one session per date (e.g. a morning and an afternoon).
Mark a session as ending on a different day for late-night events (e.g. 9pm → 2am).
Set a default capacity per session or cap the whole block.
When you edit a session's date or time, an "Email attendees about this change" option (on by default) notifies just that session's attendees. Moving a start time keeps the session's duration, and Bix blocks exact-duplicate sessions.
A session's capacity can't be reduced below the places already booked - if Bix won't accept a lower number, check that session's bookings first.