the points about using a drill to drill holes are well taken. However, I have drilled many thousands of shelf pin holes, enough to have tried various jigging approaches. I have used sleeve jigs, vix bit jigs and portalign jigs. I have used them all day long, enough to run into the ergonomic problems, the wear problems, you name it. I have seen how sleeves clog the flutes of the drill bit with sawdust. to get a clean entry hole with a drill bit in chippy veneers you need a spur point bit. with a spur point bit you have to bring the drill to a stop before loading into a sleeve or you'll blow the spurs in no time. waiting for the drill to coast down 1400 times is an expensive waste of time. vix bits too clog with sawdust, jamming the outer sleeve. then the sleeve spins against the template, rapidly wearing the bit and the jig. I have worn out plenty of both.
with the plunge router jig I'm using now, the jig registers a pin in a hole that does not have anything spinning in it, nor does it have sawdust passing through it. wear is negligible. the power draw and weight of a small router is similar to that of a handheld drill. the cutter is unrestricted, so sawdust is freely ejected and sucked up immediately by the vacuum hose attached. the weight of the tool is supported by the workpiece at all times except during repositioning. the plunge mechanism gives me squarer holes than a handheld drill and the depth stop mechanism doesn't impede sawdust flow.