Good stuff to know.
I use dxp as a chance to get some 99s or costly training out of the way. This time around, it'll be 99 Prayer for sure and hopefully 99 Smithing as well. Aside from 99s, I'll also be getting 96 Summoning. Those are my three main goals. I also try to use up all the protean items I've saved up as this is huge exp and pretty quick.
I hear what you are saying about trying to maximize Dungeoneering and Invention during dxp since those skills need a lot of experience, but for someone like me who would like more 99s, I'm not too concerned with those skills right now.
In any event, I'm always glad when these events roll around as they allow for maximization of time and resources to get the most experience. I'm ready to have no life.