I've been told it has to do with the respective airline's local FSDO(Isn't standards in their name?). Some are cool with it, others are not. I think Express Jet will take you in up to 40 hrs short. I have a CJO at one of the companies that requires 750TT. Currently sitting around 650TT with all of the other sub-category boxes checked trying to scramble and get to 750 before my written expires in July. I'm NOT interested in retaking it.