Was it out of "german professionalism" , for bureaucratic reasons or something else altogether?
Asked and answered!
https://www.reddit.com/r/AskHistorians/comments/8g0mm2/why_did_nazis_keep_such_detailed_records_for/?utm_source=share&utm_medium=mweb3x
Hope that helps.
Credit to u/mikedash on the answer itself!