I was under the impression that Flaps 5 is the standard takeoff setting for the 737, and certainly would be company policy if the company was flying mixed fleet.
That depends on company policy. In my outfit, with a mix of -700 and -800s flaps 1 was the standard take off flap setting. Other companies might decide otherwise, as far as i know ryanair uses flaps 5. There are a lot of factors at work deciding those standard settings, such as average experience level, fuel saving, usual airport type used. In FRA we always used flaps 1, the runways are too long to care about a lower flap setting (1 through 25 were the normal take off flaps settings for us). Good fun to take off with an N1 of 74% or so and then getting that almighty kick in the behind at thrust reduction altitude
