Or, to answer the question in the title: whenever you feel like it. To my opinion, there's too much talk of how you should only run a ship in a single configuration. Interceptors MUST have PTL or are useless, if you don't put VI on Whisper you are making a mistake. Han without 3P0? Inconceivable!
On the hand people are complaining about the monotonous state of the game, on the other hand people are themselves unwilling to take a list in a different direction, to try something new. Too scared to run something that might be called suboptimal. Where's the innovation?
I'll tell you that 4 naked bombers with 2 alpha interceptors doesn't work as a list...
4 naked bombers with 3 Academies worked quite well for me
I might try that. To be fair, my opponent played it logically and nuked my alphas before they did anything, the 3 Academies is probably the better choice.