mech Roller vs Mech flat tappet cam Q

I recall something about bushing the first two lifter bores on the right bank when using a roller but I can't for the life of me remember why. I haven't touched a BB in decades.

There are now pressurized pin oiled roller lifters on the market so using them in a street car isn't that much of problem anymore. It was the excessive time spent at idle that would cause problems.