According to @mak it's currently 6h. Having this lower makes it possible for the phone team to access new artifacts quicker (similar to our CI repo which is trigger based). Something like 1h would already help a lot. Given the currently upload rate most of the time the job would not have to do anything anyway. Should there be more uploads and we want to trim down archive churn we could increase it again.
This is a task on my list, but it will take a lot of work and time to resolve properly. Dak isn't really designed for this, so some changes will be needed (just a normal dinstall run currently takes more than an hour alone).