Global Aviation SA in Greece say their average CPL/ME/IR duration is 30 days, with some students finishing up in 20 days and some taking 50.. If they can push the whole course in 30 days, I don't see why you wouldn't be able to do just the CPL in 3 weeks.. really, as long as the WX plays ball, instructors, examiners and planes are lined up, the rest falls down to yourself