GMAIL is one use case, and it was one of the original services from Google and so it has one of the largest "bake" times with regards to knowing how to keep it

GMAIL is one use case, and it was one of the original services from Google and so it has one of the largest "bake" times with regards to knowing how to keep it online. Every service/team has to go through a period of growing pains as they learn, improve, and fix the code to be more stable. You can't just take the learnings from one service and apply it to another, it has to be architected and written into the code and most teams start each new project/service with fresh code.