I may add this on TZ-4a:
To Release or Not To Release?
If your final modifier is low you may elect to not drop your bombs and Go Around or Bomb the Secondary Target.
I imagine that this simulates how the Lead Bombardier looks through his sight and can see how his aim is and thus can decide if to release or not. After all, he is in charge during the bomb run. Even though he has identified the aim point he may still judge his aim to be off.
To add this or not to add this, that is the question!