Google runs a single monorepo for 95% of its projects across the company. Google isn't perfect, but it's hard to argue that it isn't technically very good. One

Google runs a single monorepo for 95% of its projects across the company. Google isn't perfect, but it's hard to argue that it isn't technically very good. One of the biggest advantages is that there is no version chasing and dependency questions. At commit X, everything works consistently. No debating about whether this or that dependency is out of sync.