They started questioning telelphone nikkahs & only nikkah cases in 2009 as now they look for proof of relationship and not just marriage. They gave those cases a hard time, some took 2 years or more to complete and some who didn't respond properly to their objection letters were put in an interview queue. So after that people actually started doing full rukhsatis and provided lots of pix, recent contact proof etc so they can see the ongoing relationship. Nowadays most cases provide alot of proof of relationship, this is why there are not too many interviews. They usually ask for an interview if they have doubts about the authenticity of the marriage & relationship so this is why you don't see too many interviews as people now provide with them enough proof to convince the Immigration officer.