I use those shortcuts as well, and often change things in 5% or 10% jumps. This is a really deep topic though, and some of the issues are from cumulative rounding errors, which can happen if you stack lots of layers or stack layer effects. It’ll also depend if you’re just moving sliders around until things look good (which is great!), or if you’re doing something that require exact values (building LUTs to process map tiles etc).

My main concern is that information is being thrown out at the input UI. As far as I can tell, Illustrator stores opacity as 8bit values internally. This can be tested by using the blend tool on objects with similar opacities.

I just want our tools to be better.