Hello there,
Still new here. What is the best strategy to learn when to trigger the transitions for songs… other than buying a BB2 and use autopilot 
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For instance Roxane,which has lots of parts, and transitions of various lenghts…
Nothing beats practice 
For some complicated songs, I make marks on a song sheet to remind me which part I should be transitioning to. That also helps if I accidentally trigger a fill instead of a transition, I know how to “catch-up” the song when an opportunity presents itself.
Writting a little cheat sheet is an idea.
Maybe annotate a lead sheet or something like that.
But yes, I was of the opinion that I wpuld just need a lot of practice to be able to recover from a live malfunction