First-response time matters, but it cannot describe support quality on its own. Teams should also monitor resolution time, first-contact resolution, handoffs, repeat contacts, and customer satisfaction.
The relationship between metrics is more useful than any isolated target. Fast responses with many handoffs often indicate routing or knowledge problems. Longer resolution time with fewer repeat contacts may mean issues are being handled more thoroughly.
Segment results by channel, issue type, and customer group, then set improvement goals for each queue. Stable trends and explainable changes are usually more valuable than a single attractive average.