Depending on the deposit at some stage one might switch entirely to RC drilling to get lots of information cheaply particulalry if the deposit is large e.g. Iron ore, Nickel Laterite, lateritic Au. For something small and geologically complicated e.g. epithermal gold you might drill RC for a few hundred meters and then switch over to diamond as you approach the target... or cut mutliple holes from the same parent hole as you can control the direction of the rods. Both will save you money and probably time.
