I pre-cache for speed, verifying records that have expired since I retain the expired records for sites that have intermittent DNS issues and also to throw in domains that I do not use in the off chance someone is logging where I go and when. They will see the Cloudflare top 20K domains hourly. Myself and family members have been able to access sites when others around the internet can not due to infrastructure related DNS problems. In other words, when others will say "It's always DNS" for myself and family members that is rarely the case as DNS records do not change as often as people seem to think they do.