[abalone]

Or there's 3.5: separate services where it makes sense, but not necessarily small in number. "Makes sense" would entail things like, does it have distinct resource utilization or scaling characteristics, or do you want to enable your service to more gracefully degrade if that module becomes unavailable.

(This is basically the definition of 3 without the implication that it will be rare.)

As opposed to 4 which is about proactively breaking everything down into the smallest possible units on the expectation that the added complexity is always worth it.