Hi Eric,
The best place to ask this is in the GITHUB for the dataset you are interested in. My fast answer would be not very often as rural buildings don't change much the impact would be more around urban and sub-urban centers. For the US, the only time we can get clean imagery is in summer. That means we don't get that data until fall. Then it takes a great amount of time, space and processing power to convert that imagery into map tiles which then can finally be scanned for new building footprints.
That being said, we did just that in 2022 https://blogs.bing.com/maps/2022-01/New-and-updated-Building-Footprints so there could be more coming if bing maps does a big enough imagery update to justify it.
Sincerely,
IoTGirl