Ann: Appointment of Managing Director, page-8

PetrStiff, short answer is no, you wouldn't drill down an orebody. Although it sounds counter-intuitive, you actually get more useful information from drilling across it.
In a lot of ore-bodies the grade will vary in 'layers' from the waste-ore contact, through the guts of it, and then the opposite ore-waste contact. Sometimes the contacts will be where the better grade is, sometimes the middle, sometimes it's disseminated evenly throughout, and sometimes it's in random high-grade nuggets or veins.
Drilling across it also gives you more information about the thickness of the orebody. You don't have to hit it perfectly normal to the dip, but with multiple holes and/or core you can calculate the true thickness using multiple angled intercepts.

The only time that I personally know of explorers intentionally drilling down the orebody is if you've got a reasonably uniform orebody and you want the maximum amount of core/RC chips for metallurgical studies.

Also drilling in the same orientation as the structure of the rock can lead to nasty deviations, as the layers in the rock can mess with where the drill bit is going. Drill rods look solid, but once you've got 100m of them strung together they're like a pool noodle and they'll just follow a path of least resistance if they intersect a soft/hard boundary at a shallow angle.