When should you go with global load balancing versus regional?

Hey everyone, I've been mulling over how we approach high availability and performance for our distributed systems. We talk a lot about load balancing, right. But I'm really wondering about the pros and cons of global load balancing versus just regional load balancing inside one cloud zone. Think AWS Route 53 with latency-based routing or Azure Traffic Manager for global, and then, well, just a standard load balancer for regional. When does the whole global setup get too complicated for what it's worth in terms of availability and speed? Are there times when just sticking with regional makes more sense, even if your service needs to reach people everywhere?