Amendment updating is done nightly, and the results are on "congress.gov", which is the user-friendly access interface. The XML dump is the raw data, made available to the public.
"ammendment updating" would be the meta-history of the bills themselves, right? I meant the applying passed and signed bills to the overall body of all. When is that done?
The user guide for the XML data is on Github.[1]
[1] https://github.com/usgpo/bill-status/blob/master/BILLSTATUS-...