It would depend on "how things are wired together". Now, it's great if they are "wired together" in such a way that one need not give it any thought. But whether we're talking EC2 instances or containers, at some point one has to think about it, e.g. two instances talking to each other, one being on the East Coast USA and the other in the Midwest, or West Coast, vs. their both being in the same datacenter. That's at the extremes, for sure, but maybe even intra-dc clustering has to be considered explicitly for certain applications? Maybe not?