There is no correct line to join a circuit crosswind. Stating that you always cross at the numbers suggests ‘bible of fool’s mentality’. The best place to cross is based on your judgement of where you want to turn downwind in the circuit and the pattern you want to fly from that point. Careful analysis of traffic in the ATZ using the radio and lookout may also cause modification of this line. I personally want to be on the line that everyone else is not taking having had a couple of near misses on the dead side. Many pilots are still descending on the crosswind leg and if you all take the same line guess what the outcome may be!
Flying a straight line in my opinion is fraught with danger on the dead side, try keeping the straight line bit to a minimum, make plenty of wing dips to clear the blind spots too.
Constrained rule based procedure is great in the classroom but flexible best practice based on current situation is superior in the air