The Friday-afternoon calls are where I’d make the promise very specific: “I’ll check the route and call you by 3:30 to confirm whether we can get there today.” Only use a time you can actually meet, but it gives the customer something firmer than “we’ll try.”
I’d also give whoever answers the phone a clear limit: they can collect the location, what the caller is seeing, and their availability; only the person managing the schedule can commit a technician or arrival window. The same limit should apply to an answering service or AI.
Anthony’s flex-slot idea could work well with a release time, too. If it’s still unused at noon, offer it to a nearby customer on a cancellation list. That way you have room for urgent work without leaving the opening unused all day.
