rod cap oil slot?

I'm building my first 360, getting ready to drop in the slugs, but I'm confused about these slots cut into some of the rod caps that are supposedly for oiling. The book "How to rebuild your small block mopar" says they need to be installed facing the opposite cylinder (to oil the opposite cylinder). I'm scratching my head thinking... no oil is going to quirt out of those slots, it makes more sense they are made for oil to get in to the rod bearings.

Besides, only three of them have these grooves in the cap, the other 5 dont. Do I need to worry about the direction they are facing as the book suggests?
Also, if they are for oiling the rod bearings as I would suspect, wouldn't they need a hole in the bearing as well? Otherwise only the backside/journal side of the bearings will get lubed...

Anybody know what I am talking about? Thanks