implementing a global distributed cache, when does it make sense

were thinkin bout a global distributed cache for our microservices architecture. gotta cut latency for our users worldwide. right now, we use regional caches, but read times are gettin slow for folks far from our main data centers. has anyone pulled off a real global cache (like, with Redis Global Datastore, DynamoDB Accelerator, or somethin similar) Success stories tho What were the big hurdles w consistency, cost, and just runnin it all Are there specific times when the good stuff clearly beats the bad stuff, or is it usually smarter to just stick w good ol regional caches