TRENCHLORD
Banned
I'm not actually aiming to lift heavier, I thought you were doing like 3x10 sets or something which surprised me, I seem only hear about 5x5s from people who have been lifting for more than 3 months
5 x 5 is just a catch all really. It ensures adequate weight and adequate volume both.
Time under load/tension is actually the more important factor as far as the volume aspect, which is why a number of rep schemes seem to work provided you're going heavy enough. That's why rep style/speed is also a big part of the equation.
5 x 5 is a great place to start, but you'll want to judge for yourself whatever it requires to induce some good soreness the next day.