Define "unneeded". We always are told to do regular check ups, so in case we have something like cancer or other serious illness it is detected early. That means two things: people go for check ups at the first symptoms or even being healthy ("unnecessary") but also that usually illness are detected early, when they are easy and less expensive to treat. You make a choice, pay for "unnecessary" visits to detect things earlier or treat things when they are serious.

On the other hand, you might mean unnecessary test made to increase the bill. Which would be the result of paid doctors wanting to improve their "productivity stats". How you measure things have impact in the results your get, since people usually know how to "play the systems" to their short term advantage.