I normally have one on the go (training up) and once they get to Elite I start looking for another harmless one with a suitable backstory to train up. If I'm happy with their voice I'll let the Elite one go & carry on with the new one.
Yeap, that's doable lately after they fixed the slf crew voice bug.
I was really miffed back then when, after finding a crew with a nice British accent (and who called me Sir) while looking good enough so i dont get scared to death by looking at her picture, only to find out that at next relog her accent and voice lines reverted to the bog standard US accent.