A fan spread of holes off the same setup decreases drilling time associated with moving onto a new hole, moving rigs, running water hoses etc but you still need to put down casing for each hole you start (the drill rod goes down the casing pipe until you are drilling in 'fresh rock'.

The 100 to 200 meter holes will probably average 100-150 meters per day based on 24/7 drilling with two shifts. With winter drilling weather is both your friend an enemy. Easy to get around but you need to hrat heat your water constantly to prevent freezing so there are no shut downs unless you like hoses filled with ice and cracked pumps.

300 meter plus holes start to slow down. Every meter after 400 meters get slower and slower so while you may averaging a 100 or so a day on the first 500 the next shifts production may be 30 m or nothing. It becomes technically more challenging the deeper you drill and mistakes become costly. Drillers dislike short holes because of the time lost to setup, love those 200-300m holes because of performance bonuses, and not to surprisingly dislike the longer holes.

Drill holes can be abandoned for a number of reasons. Sometimes it’s because of rock conditions where the ground is so fractured that you can get core, or hold water to lubricate the drill. Other times the hole drifts so much off target that it is restarted (try taping 20 straws together and see how far you can bend them). Other times drill rods get broken off in the holes and they can't be recovered. Many many reasons for abandoning a hole.

Drilling through a fault is not in itself a big deal. Most faults are solid rock, quartz/carbonate filled, metamorphosed shear zones or relatively thin. Whatever they are you typically can't avoid them if you plan on getting to your target zone.

My read of the drill sections is that the HGZ is plunging (getting deeper) with every step out. As such the geologist will like to use step outs from previous holes in order to increase their odds of hitting the target on the next step out hole. Those nice straight lines and extrapolations are great until you can't find you next target. At that point the geologists start to earn their money figuring it out.

I suspect that only one drill will be doing step out drilling, two will be doing infill drilling behind it, and one for exploration drilling. At 100m+ (10+ grand a day) per drill you have to keep them in drill targets and drilling. Standby costs are expensive. It’s exhausting to keep 4 drills running from a geology perspective in that you need targets in advance of their move and manage the rigs. If all four were doing step out drilling and you start to miss your target it would be chaos.

... Been There