When we look at our avg. in-app time per user - it is between 1 and 4 min a day (based on Fabric's daily report). That alone doesn't give us enough. Even when we look at statistic on average numbers by vertical (40min a month per user for Travel & Lifestyle) we could be under that number or way above.
To really find that we are going to analyze our Fabric logs we have started populating around mind August. And, so that we don't get caught in various vanity metrics it is really important for us to see what those users are doing. Stay tuned....
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source for statistic on average time per user a month:
https://www.statista.com/statistics/243779/total-minutes-spent-on-average-app-by-category/