I've been working on problems at various scales from subatomic to galactic scale and about everything in between. At some point, when you're genuinely interested about what you do, you build mental bridges between domains and scales and values and units, you... connect some dots. You start understanding what a log/exp is, what that "shooting through the roof" profoundly means. By understanding I mean you start feeling it with your gut. So when someone talks about one Zm I could take it as a pure value, but I could try and get the feel of it. It's overwhelming, so much so that I can physically feel the cognitive weight of it on my mind. So when I make some conversion and find that 1Zm is about 100'000 light years, and I know (whatever the light-year value means, I take it as pure, transitional value to an item of knowledge) that the Milky Way is about that size in diameter, only then do I feel the absolutely immense size of our galaxy. I must insist that it's no more the vision of the galaxy that gives weight to a Zm to me, but the Zm that gives the incredible sense of dimension of that pack of matter.