Diminishing returns at some point, but, I think the counterpoint to this is companies who are doing a single huge manual deployment every month (or less) which is scheduled into a 4-hour outage window where many if not all services will be down for this period.

I do agree there isn't a lot of delta between a company doing 2 or 10 deploys a day and a company doing 1,200, but, there's a huge engineering gap between companies who do approximately .03 deploys per day and those doing multiple.