Get me straight on Valve adjustment Intervals

Hey all....

Can someone get me straight on the valve adjust and service intervals for the 4V and 8V motors? Whats required, recommended and considered overkill? I've changed the oil and plugs, but not CARC or Transmission oils. IME, this is mostly overkill unless riding in severe conditions, dust, rain, heavy loads, etc.

I'm at 13K on my 4V GRiSO, and if I remember correctly, the Original owner (on this board) never had an adjustment and I when I bought it from MI in 2016, it was just shy of needing one. The bike runs so sweet and sounds good, but I imagine I am due.

On the 8V Norge, when I was trying to diagnose the rev problem, I had the valve coves off a dozen times and the valves were adjusted at 5K. I'm now at 8K.

I do know I need to do the swing arm and steering stem bearings and am dreading it.....

The amount of oil is small, and the cost is cheap.
Diffs and gearboxes are expensive.
Follow the factory recommended intervals or;
Be lazy, be cheap. It's your choice!

I haven't done high mileage on my bike, but with my work utes (suv/small truck) factory claims diff and gearbox are sealed for life. CRAP!
I do regular full oil changes of these items. At $1,300 for a diff rebuild and $7,000 for a replacement gearbox, multiple oil changes are cheap.
Thus far I have doubled the life of these components compared to the average of those who do nothing.

Manual says 950 miles for break in period then again at 6000 miles, 12000 etc...
Every 6000 miles actually. Both 4V and 8V engines.