Great article! I love the Push, Pull, Legs split.

I agree with the idea of 3 days for beginners and 6 for advanced lifters. But, if you find yourself somewhere in between I have had some success with 4 days in the past.

I used to go Push, Pull, Legs, Rest, Weak Points.

In the fourth workout in the week I would focus specifically on my weak points. For me that meant delts, hamstrings, and triceps. But, it's different for everyone.