I had this discussion about 12 months ago and was told in no uncertain terms I was wasting my time.
Now I will say it unequivocally, the cam and shaft on E61 group heads need periodic lubricating with food grade grease, I use Inox from Jaycar electrical, a tube will last forever.
The orange cam in the illustration and its shaft are the parts that need lubricating.
I give them a smear every time I descale (approx 3 monthly) its a simple job, 5 mins at the outside and well worth the effort, the difference in lever operation (smoothness) is very noticeable.
