Agreed - Chris Harris in New Hampshire has a couple of detailed vids showing a meticulous sequence of toothbrushing the splines of a gearbox input shaft with a modest blob of Klübers Lubricants 'Staburags' NBU30 PTM.
I would think that kind of maintenance is a once-in-a-lifetime job, and it wasn't ever done at the factory in Spandau. I've done it, exactly as he's shown, when I installed the new Thai frictionplate with the longer hub, but I don't think the greasing is really necessary. So long as the bike is not one of the rare few which were misaligned back in the early noughties with the risk of premature spline wear, just ride. Lubing an out-of-true interface between bell-housing and gearbox would not prevent such wear anyway.
Fact remains though that BMW got away for decades with a badly-designed single-plate, Austin Mini-styled back-to-front dry clutch. Not to mention the appallingly inadequate pushbike slave cylinder, which can be troublesome if the hydraulic fluid in there isn't flushed out and replaced every twenty seconds ( ! )
Viz their abandonment of the design in 2013 in favour of a cheapo Chinese-outsourced wet clutch.
Moto-Guzzi using a similar single-plate dry friction plate design at least incorporated a VW style thrust bearing in there, to avoid misalignment and excessive wear.
AL in sunny Andalucía.
