No, the Data collector does not need to be re-run more than once per web session, so it's a good idea to put it on your site in a location where it can run early, and then be able to skip it if it's been run. While running the data collector multiple times in a single web session will not cause any harm, it creates unneeded load on the customer and servers. One way to accomplish this is to set a value in the session once you know the Data Collector is done, and then skip the Script tag we provide if that session flag is set. If that seems complicated and hard, you can disregard it and let the Collector run each time.