Flash Briefings - how often?
You need to feed the machine - so update your Flash Briefing regularly.
Customers and potential customers listen to their Flash Briefing throughout the day, and hearing the same news repeated can create a negative experience.
So update your feeds as often as possible, so they always have new content to consume. That's the best way to engage customers or prospects and encourage ongoing use.
Then it's part of their daily routine - or preferably part of their Routine (the name given to the set-up where sequential Briefings are preceded by Alexa-read weather and travel reports) - and listening to you becomes habit-forming.
Otherwise they will hear the default apology that your Briefing is not available; think of the harm that will do to your business or brand, your product or you personally.