I call everyone back in the evening — it's always been enough.

The problem is the timing of the callback: public speed-to-lead data shows a caller becomes very hard to qualify after 5 to 10 minutes, because they've already called someone else. Calling back at 8 PM, you're cold-calling people who had chosen you at 11 AM. Signal turns your evening call into a mere confirmation: the request is qualified, the appointment often already booked. And real emergencies (score 4 or 5) can't wait until evening — escalation alerts you immediately, you stay in control.