DNS_Request redirects traffic slowly

No problem. There's always a tradeoff when planning for failure. How badly do you want to impact the customer experience to plan for the occasional outage? By keeping TTL's really low, particularly in a delegated scenario, each request must be made twice (once to the authority, then to the GTM) and in high latency environments this can impact the perception of the overall performance. A higher TTL may result in a longer outage, but won't impact the day-to-day of normal operations. Knowing your audience and the landscape in which they reach you will help in finding that sweetspot.