We use Google Analytics to measure traffic coming from our marketing campaigns. For one of our customers we are currently running vastly different campaigns on the same site. To easily split the results we have made a 10 second on site goal for the specific pages on the site. In Google Tag Manager I have set up a Timer to fire after 10 seconds on specific pages.
Example: Campaign A has a landing page for /housing/example/1. 10 seconds goal A is firing on all /housing/x pages.
Campaign B has a landing page for /vacancy/example/1. 10 seconds goal B is firing on all /vacancy/ pages.
When looking at the results for our LinkedIn Campaign I can see the regular duration goal from Google Analytics, which is also set to 10 seconds, fire much less than the event goal fired from Google Tag Manager. This should not happen seeing as the regular duration goal is firing on all pages and my custom goal is only firing on specific pages.
I asume this is because the duration goal from Google Analytics only fires once per site and my Google Tag Manager event will fire every page.
My question is if this assumption is correct and if there is a way to set custom event goals to only fire once per site in Google Analytics.