On my pull-type 7 ft Woods mower, I go 8-10 hours on the U joints and 20 or so on the spindles. On the four rolling rear wheels, I give them a quick hit of grease every time I mow my 2.5 acres. It only takes a moment for that.
Sure, the wheels are maybe overkill but it's just a metal shaft in a metal hole so the grease is gone quickly. On the plus side, in many decades of mowing with different mid and rear mowers, I have never replaced a stub wheel or spindle or anything other than a belt. My equipment feels and operates like new and I like that as well.