Here’s a tip that’s especially important to anyone working with a single-page application. Google Tag Manager persists items in its data model until you either manually delete the variable and/or its value from the data model, or until the user browses away from the page. There’s nothing as annoying as the example in the image below, where a value that was set for an earlier Tag is resent with a new Tag, even though the purpose was to leave it out.
