There is a bit more to it than that I would say that drilling (just straight drill, not coring) will take that amount of time. Assuming this rig is probably small (single) meaning it can only hold 1-30 ft joint of pipe in the derrick, and the fact this is hard rock you will probably on have 30 ft of core barrel. This means that you will be able to drill 30 ft of core and you must pull out of the hole every 30 ft to break out your core. The drilling time will be greatly increased by doing this because your ROP is much slower when coring to make sure your core is in good shape when you get it out (it might be 12 hr round trip for 30 ft of core). Remember this depends on a lot of things (length of core interval, rig type, new bit?). I dont want to be the Debbie Downer here but I would estimate that @ 500 meter hole depth, through hard rock (granite, hematite, pyrite stringers, quartz etc) the estimation would be more accurate at 3 weeks per hole. This would include rig moves which can take a while with older equipment. That means we are currently on hole #4. Just a drilling engineers perspective.

IMHO as always

DBD