I'm going to assume we're restricting this to theater of the mind mode.
You can use the same rule with battlemats and such of course, in which case instead of DCs you just roll for how far you move exactly. I have a set of chase rules on my blog that use this approach, and I've used these extensively in campaigns for foot chases, horse chases, ship chases, and so on.
For theater of the mind mode, Spitemaster is correct: you don't roll unless it's interesting. If people just say "they move," you let them move, just as you don't make someone roll Athletics to jump over the curb. Use the general Passive rule; if the DC would be 10 + their bonus or less, don't worry about it.
You're using it when someone wants to do something that you as the DM think might take more than one move, or be dicey, but you can't "prove" it because there's no battlemat and the players feel like you're against them if you just say "no."
"Can I run around behind the bulette and flank with the fighter?" asks the dwarf? Hmm, that's a lot of move for a dwarf... Roll it. DC20, you don't make it you end up along its flank proportional to how bad you miss the roll. Roll a 1 and maybe it gets an attack on you.
"Can I catch the fleeing orc?" Maybe, maybe not... Roll it. Beat the orc's move as a DC yes, don't beat it no.
"Can I light the fuse on the bomb and run and jump in the ditch before it goes off?" Maybe, maybe not... Roll it. DC based on how reckless vs. planned I think you're being. If you set up the bomb, DC 20, if it was just lying there and you have no idea how long that fuse is, DC 27. Maybe if you get above 15 you get to save for half damage.
A Dash (or in older eds, a double move) has a non-deterministic effect. If you take your whole action to dash, well of course you can get around behind the bulette. To catch the orc, I'm assuming you were Dashing because he is too, if you aren't you probably don't even get the roll (unless your move is way higher than his to where it could be competitive). Same deal with the bomb, if the ditch is only 30 feet away why would you be rolling? I'm assuming it's a stretch. As usual for 5e, apply advantage or disadvantage for complicating factors (poor footing, having to Disengage first...)
Trying for too much precision is against the point of theater of the mind.
You DC based on how hard you reckon it is and come up with tradeoffs to give the PC interesting choices - the main complaint of being off the battlemat is not having tactical decisions to make. "DC 30 if you go way around the bulette, DC 20 if you're willing to risk an attack in its reach." Rulings, not rules is the heart of theater of the mind.