Not sure if it matters but i use Shimano reels and i oil them a couple of times a year and clean them less than that. Maybe once every year or so they get a strip down cleaning. Of course if they get extremely dirty and start grinding then i would take care of it.
I started using Rocket Fuel Reel Oil a few years ago on my bearings and that might contribute to the reels feeling good for a longer period of time?
If i strip them down i use lighter fluid to soak the bearings, dry them out and them apply the Rocket Fuel again. All the other areas get a wipe down to get dirt and grime off of it. My reels always feel good with this routine. I never dunk my reels in the lake or creek as i have seen others do.
Oh and i can't remember the last time i greased my reels, i don't see a need to have a thick lube on a reel that i want to spin as free as possible. Maybe others do but not me.