Basically: you can try to keep a low TTL DNS, but it'll be more DNS traffic, and 5-10% of traffic takes forever to cut over because nobody respects TTL. Worst case you have just as much down time as before, best case most of your traffic is recovered in a few minutes.
It may be useful to note, for whoever is reading this, that low DNS TTL only ever makes sense for anything that you can do a cutover either automatically or on short notice, not for all records. Otherwise, you are now at mercy of outages on your DNS providers.
Just leaving it out there so one doesn't get the idea that "low TTL == Always Good"
Etsy implementing multiple CDN (7 years ago, the CDNcontrol project looks abandoned): https://speakerdeck.com/ickymettle/integrating-multiple-cdn-... https://dyn.com/blog/speaking-with-etsy-about-multi-cdns-and...
Basically: you can try to keep a low TTL DNS, but it'll be more DNS traffic, and 5-10% of traffic takes forever to cut over because nobody respects TTL. Worst case you have just as much down time as before, best case most of your traffic is recovered in a few minutes.