> They've enforced style by mandating committers hook a linter into a git pre-commit hook

Style-related presubmit hooks are a part of every project at Google. Plus readability requirements, etc - style is kept pretty damn consistent.

> compilation time hasn't been a huge problem since the languages always support incremental/partial compilation (Java/Lisp for the most part).

This is the far more interesting problem to solve at scale with a single centralized repository.