I loved to do that in Everquest.

Started on my mage who could summon a ring that instantly cast levitate on you.

So we had games getting up to, and jumping off of, really tall structures and playing chicken with the ground lol.

On my bard, the combination of raw movement speed and a Lev meant getting into places not designed for players, though I will say they did a good job of making sure you didn't die out of bounds, back when you had to recover your gear from your corpse.

I only had to petition a GM once to get me unstuck, lol.

They just teleported me to the current expansion at the time "hub city."

Never got into speed running though, and I don't think my attention span would allow for it. Respect and all, its impressive what some people can do, just not my thing.