[utopia]

I've done my own valve clearance checks three times now.
I also have enough engineering experience to have a decent amount of "feel" with measuring systems.
Just thought I'd pass on what I've learned from work on my own M750, namely ....

The results you get are significantly dependent on the method used.
I favour the method used by Chris Kelly to check the closer clearances but I also measure them directly and compare the results.
Also, no matter what method I'm using, I usually go through the whole lot two or three times, keeping notes as I go.
I always get discrepancies and I'm not satisfied until I have reasonable parity between both the different measurement methods and the repeated attempts at the same method.
This whole process usually takes me two or three days and this is partly because I like to leave a decent gap between my various attempts to reduce the chances of robotic repeats.
I have found in the past that after a few attempts I become much more confident in the validity of my individual measurements and my overall result.
In the past I have been able to detect differences which arise simply from, for example, the method that I use to load the closing rocker.
If you think about it, this isn't surprising as you are measuring the effect of an assembly of parts, each of which has a working clearance.
I also bear in mind that oil on the mating surfaces can affect the results.

I tend to be happy to adjust any clearances which are a little tight and need opening up a bit but I'm more wary of adjusting any that are loose and need closing up ... particularly the closer clearances.
I also disregard any recommendations to aim for zero clearances because I'd rather have a little noise than risk a damaging interference.
Valve clearances which are a small amount out of tolerance, as long as there is no interference, should not cause what you could call a running "fault" with the engine ... they would only fractionally reduce the running efficiency.
Finally, I keep detailed notes of everything as I go along. I also edit these notes into a suitable record for future use.

Personally, I'm not a fan of rubbing shims down to reduce their size. I tend to prefer buying a new shim (or accepting a small amount of difference from perfection).
Its too easy, in my opinion, to change a dead flat surface into a curved or tapered one in the process.
Also bear in mind that the shims are hardened (probably case hardened if they're original Ducati shims but there are aftermarket shims which are hardened right through .. or so I'm told).
But I know there are plenty who do rub shims down in size and seem to get away with it. ... you pays yer money ....

A mirror will provide a reasonable flat surface to work from if you do decide to rub shims down.
It can also make a useful substitution for an engineering surface plate for use in making measurements.

Sorry that's all a bit lengthy, both in words and in the work suggested, but in these days of social isolation you might as well spend a bit longer in the shed, eh ?