Hi Lisa,
Yes, this should work, but be sure to include a logic in the choice steps that will exclude anyone who already received the email (just a good precaution to take). We do something very similar to what you described. Our batch campaign for the email has the following flow steps:
If Email Flight = A, Send Email EXAMPLE.
All else, do nothing.
Wait 3 hours
If Was Sent Email EXAMPLE, do nothing.
If Email Flight = B, Send Email EXAMPLE
All else, do nothing.
etc.