I know I'm a bit fuddy-duddy and old-hat with my Slocombes but I do like them for starting a Jobber.

You get that 60 degree cone to align the bit PLUS a perfectly concentric pilot hole to clear the awkward drill centre.

The Jobber goes in real easy to the bottom of the pilot by which time you have a much better hold on centre.

I'm not going to argue the why's and wherefore's, but I think they are neat