Cycle-and-soak sprinkler scheduler
If water runs down the sidewalk while the sprinklers are on, your heads are putting water down faster than the soil can take it in. The fix costs nothing: run the same total time in shorter cycles, with a soak in between. This works out how short, and how many.
Why this works
Water soaks into soil at a limited rate. Sandy soil can take in an inch or more an hour; clay may take in a tenth of an inch. Spray heads often put down over an inch an hour, so on clay most of a long cycle runs off. On slopes it runs off even sooner.
Short cycles stop each round before water starts to run off; the soak lets it move down into the soil before the next round. The total water is the same; you just stop losing it to the gutter.
The intake rates used here are typical design values for each soil and slope. Compacted soil or a hard layer near the surface (very common on new-build lots) cuts them sharply. If you still see runoff, shorten the cycles further.