For folks criticizing ZephyrZ's post, bear in mind that he's not saying that those level 50 cross-class skills aren't insanely useful, just that they're not NECESSARY. Not having them will reduce your success rate, but not eliminate it. Though, by that same token, I'd bump his suggestion that BB is "necessary" down to "Nice to have". After all, you can complete even Masterbook II's without it - you just won't ever make it higher than 20% quality rate, barring an insane string of Goods or Excellents (and maybe not even then).

(I'd also personally swap Ingenuity II and Careful Synthesis II in his list of priorities; the former just isn't useful after 2-star, and 2-star can easily be completed without it and for the latter, well, a powerful, guaranteed Synthesis move is so very nice to have, especially if you're not sure you're going to have Steady Hand available at the end of the synth. That's just me, though...)

It's evident that he knows how to endgame craft, and well enough that he knows what things COULD be sacrificed in a pinch. It's obvious that having all crafts to 50 is the best way to go in the long run - but it's not the only way.