my view:
1. your case has some weak point(s). you should know what it is. hope the officer will approve your case with out next call / interview
2. but if USCIS called, the call will about the weak point(s) of your case or about next interview
3. generally speaking, marriage GC requirements are low and easy to meet. applicant easily make judgement before hand the out coming of the case. officer only can make case longer but good cases almost never get denied