my technique is : use the sidestand, urban mode, put a little tipex or nail paint on the link that you start with, measure, adjust, move bike along, measure adjust, move bike along, you will notice that along the way at least one place may the looser than others, tighten and repeat the journey to verify, use a metal ruler ideally. sitting down, different modes, etc. all give a false reading, do it right in urban mode once every 6 months or so with a good chain (original is shite). take it from me, my chain broke whilst accelerating hard through 100-120mph on the m40, so learnt the hard way.
I stick mine on its centre stand, turn the preload down to 0. and ratchet strap the swinging arm up until the sprockets align and then make sure there's about 4mm of play in the chain, then turn the wheel and check it again at a few different sections, simples.
Additionally, a key point to keep in mind is that you need enough slack in your chain to allow the suspension to do its work. If the chain is too tight then the suspension travel is inhibited.
I have found that when adjusted according to Ducati and when cold the chain becomes far to tight after a run. Perhaps because the alloy swing arm expands more than the steel chain? The swing arm does get very warm. Being 6' 2" I can reach down and check tension while sat on and I make sure there is slight play when hot. I always have to slacken it a little after a service. Has anyone else found this?
I came to this thread from searching as my chain always seems slack despite checking the tension about 100 miles ago its slack again. I do though check it on the centre stand as always done that on previous bikes that had one or on a paddock stand 6 years on a GS make chain sorting a blast from the past Looks like its back to basics and start from scratch as the Ducati book says and see if its any better