1500 ft overfly
The 1500 ft overfly procedure for joining the circuit has been around for many decades. It was routine procedure before jets or turboprops were invented, and worked very well to keep you clear of circuit traffic until you had figured out where it was (ie which runway was in use).
It was not just a recent thing, and it pre dates the 1500 ft jet circuits.
Obviously it is not so simple anymore, and 1500ft may be polluted by jets..