You can architect for this though. Let's say you're a data-heavy SaaS selling primarily to enterprise, which operates their own datacenters. Instead of naively forcing all requests to go first to api.saas.example, you allow the enterprise to configure its account to first hit a cache service (that you write and distribute) located at saas-cache.enterprise.internal, allowing both the SaaS and the enterprise to save on bandwidth by not fetching the same data 20 times over.