Of those that has been the least common at my tables.

That's fair. Perhaps another style of DMing and/or a different system are more your speed.

I’ve always just treated it as a natural 3D extension of the 2D grid rules

I believe that's how it's handled in D&D too, or at least how my table has always done it. I meant more as a practical matter, you're very unlikely to have a vertical wall grid and some kind of stand of the correct height for your minis, so you can't just count squares like you would for horizontal movement. That's when the Pythagorean Theorem comes up in my experience.

And there are more then enough systems out there for everyone to find his perfect match and then some.

RAW yes, they're 30 feet away.

As a home rule, I'll sometimes run total distance = long distance plus half the short distance. That also correlates nicely with making every other diagonal count as 10'

Reddit API Fallout Crew ️

Ah yes, the "APIcalypse" or "Rexxit".

The lack of dnd-style multiclassing in Pathfinder was something I struggled with at first, but honestly now (especially with the "free archetype" optional rule) it's one of my favourite underrated things about having switched. It's not as flashy as the 4 degrees of success or three action system, but it's a really great system.

Ironaically enough, you just take either the horizontal or the vertical distance (whatever is longer) instead of calculating. I hate that rule and never use it, but that's what RAW says.

Happy cake day!