is a cdn for a wordpress website pointless if 90% of visitors are in one city?

i keep going back and forth on this for a local client. a cdn for a wordpress website makes obvious sense when your traffic is spread across countries, you push static assets to edge nodes and everyone gets a closer copy. but this site is a dentist whose analytics say 90 percent of sessions land within about 30 miles of the office, all served from a datacenter that's already in the same reigon.

the caching and origin shielding still help a little, and cloudflare in front gives me free tls, ddos cover and a cheap way to cache html at the edge, so i leave it on mostly for those reasons rather than raw distance latency. still i keep wondering if i'm paying in extra dns lookups and a tls handshake to a third party for a latency win that basically rounds to zero at that range. anyone measured real ttfb with and without a cdn on a truly local audience?