Someone like AWS has a minimum amount of time they bill for an instance for. It's usually 1 hour. If Pinterest is deploying 500 times a day, the cost of spinning up all new instances every single time would be pretty excessive. A lot of companies have a fixed set of app servers that stay up most of the time, then another set of dynamic ones that spin up and down with traffic.

So yes, it probably does mean that they are deploying more than once to the same set of servers.