I grease them at each fuel up and/or chain sharpening, have been since the late 70's.
A few years ago I was running the original 20" bar on my Husqvarna 480, which had at that time been in service since 1980, so at least 25 years. I forgot to bring the tool box (where I keep the grease tool) on that outing, and went ahead and ran the saw all day, just touching up the chain and fueling it up.
On the 3rd tank of fuel it SMOKED the roller nose in the bar. Coincidence? Could be, as that bar had cut hundreds and hundreds of cords of wood, and I had long lost count of how many chains had worn out on it.
Anyhow, never tried that again, and it was the first and only roller nose I've burned up in over 30 years of cutting.......Cliff