Fascinating read. Of course I'm no big business but for the last 20 years I've done it like this for non-critical stuff:

  - NS Records at 86400
  - A and CNAME at 3600
  - 1-2 days before moving stuff to other infra (ISP, DNS reseller, etc), switch to 600 or lower, then 1-2 days later switch back.

Can't even say why, it's cargo culting but it has always worked out fine, but ofc I'm not talking about production APIs.

And every single time there was some problem, setting the TTL to < 1minute would not have helped, so I guess I'll stick to it.