[r1ch]

The trend has definitely been towards lower and lower TTLs with cloud deployments and such. What used to be a 1 day TTL with a static host is now 5 minutes in the cloud.

Servers that use geo DNS (EDNS-Client-Subnet) also cause considerable cache misses since the caching becomes very granular.

[acdha]

Good points - also people started using more TLDs and hostnames as the average page started loading different service endpoints directly in the client, and I got the impression that a fair number of places were slow to increase their DNS cache sizes.