I think that like many things, the whole WTG, XTG, ATG pattern is talked about and used because it gives a consistent starting point for learning.

Lot's of people shave that way for ever because it works. However, the shape of the face and various other issue play into the pattern for shaving. Personally, I got WTG, ATG XTG on my cheeks, and then angled slightly off of WTG, angled off of XTG and then angled the other direction off of XTG on my neck, because that's what get's me a close and comfortable shave.

If you've been using a DE for a year and a half, you may want to start with a pattern that matches what you do with your DE.