Well, machine tool spindles are a different kind of fish, no contact seals in there for temperature sensitivity, only labyrinth types. On motor bikes it is a better idea to have REAL seals, no felt rubbish as these only collect road dirt and eat away the corresponding faces on shafts and all. Not suitable for power washes as well.
In case you like some lathe hours you may add some grease retainers in the assembly of hubs or swing arm bearings like in my photos, plus some spacers to go with real seals , dust lip types, to act on stainless. Then you grease the Timkens once, assemble all components and forget them for a few decades, mostly lifetime . Even a combination of suitable washers can save some lathe work for having grease retainers in there. Big bonus: You can be sure the grease will be confined IN the bearing all the time and will not get lost in time in all cavities in the hub or swing arm - in pounds over time.
Grease nipples on brake cams - dangerous I´d say ! The unsuspecting will grease a few times - and will end up with greased linings . Good luck when he gets to know in a non-critical situation. Better to wash the components and regrease after two or three tire change intervals, no nipples active. So grease nipples are allright in some places but not in all definitely. And yes, often the designers did not spend much time on reasonable assemblies to obtain practicality in all conditions.
Vic
swing arm with grease containers , seal holder with o-ring on o.d. to snap into seat, x-ring for sealing on ss spacers, low speed condition :
hub seals with grease retainers, ss spacers for dust lip type seals:
4 LS front wheel:
rear wheel: