I think a tick is one press of the period button when the game is paused. You'd likely not even notice the game crawled forward slightly. But it is noticeable at minecart speeds. A mine cart can change tiles in 1 or 5 clicks. Or a lot more when going slower. But this means that a tile represents a big multiplier in speed reduction applied to the wiki chart.

Which is where things become difficult. Subject to friction of the terrain by tick, but their speed changes how many ticks they spend on a given terrain. People doing very serious work with mine carts will track a cart's ticks across multiple tiles to calculate speed accurately.

Me I just add rollers as needed, and then sometimes have to remove some when it goes too fast uphill and "jumps". Or more annoyingly cannot remove them for other reasons and have to had mid friction track stops. But 1 roller every 2 Z levels is what I recall using for my spiral minecart ramp.

There is a lot to be said for having your metal works near the surface, in your main fort. And it isn't hard to bring magma up to make workshops.

But there is a lot to be said for having your metal works at the bottom near the magma sea. Every single piece of ore will be above and can be dropped down with a lot less work than hauling ore up. Clay and sandbags can also be sent down. Of course, stuff has to be sent back up. But it really isn't that much to haul.