Ghost Route
Let the Ghost Route plot the line
Working out which streets are worth running is a search problem. The Ghost Route does that search for you.
What it does
Tell it how many minutes you have and whether you are running or riding. It scouts routes around your area and returns the one that claims the most new ground, streets you do not already hold, for the time you have got.

Rotations
Everybody gets 12 rotations a day, power-ups or no power-ups. Each rotation is one plan request. Case gear buys extra looks at the map, more rotations and, at the rarer rung, a longer planning horizon, but it never buys a better answer than the ground itself has to offer.
Asking the same question twice is free. Tap Plot my Ghost again from the same spot, reopen the sheet, or come back to it mid-run, and you get the answer you already have without spending anything. Only a genuinely different question, a new spot or a new length, costs a rotation.
Being navigated round it
In the app, a plan can be followed turn by turn. Tap Navigate and recording starts alongside guidance: the next instruction sits at the top of the screen with the distance counting down to it, and it is spoken aloud so you can keep your eyes up. There is a mute control if you would rather run in peace.
Wander off the route and it says so plainly rather than nagging. You can rejoin the plan, or drop guidance and carry on as a free run: your recording keeps going either way, so no ground is ever lost by ignoring the Ghost.
Exporting the route
Prefer your own watch? Download the plan as a GPX file and load it onto whatever you already run with. The Ghost Route plots the line either way; following it is up to you.