Hey Marcos! Great question, we do not track "time spent" spent on a card. Since Guru is bringing you knowledge "where you work" we know users can be doing a million things at once and may open a card, read it, and keep it open while going to the next thing (which won't truly show time spent on the content).
In the Analytics endpoint, there are timestamps for each card event. You could perhaps track the time of the `card-viewed`event and see the time difference from the time stamp of the sequential event for that specific users. In the screenshot below, it was 00:00:02 between me viewing the card and clicking the card link (clearly didn't read it

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The only downside of this way to tracking is that you can't track what else someone is doing. Maybe the user clicks on the card which triggers the `card-viewed` event, but then the user goes into their email to look at something else without triggering the next Guru event. So it could look like they are viewing a card for hours, but in reality, the moved into a different application.
Not the best workaround, but like I said before, we don't have a direct endpoint to track time spent.
