Jikes, I am kind of used to swift transfers taking 1 day these days, let alone sepa, that should be max minutes. And I have not seen them take more for quite a while. Did not know it was that different in DE.
AFAIK they have a limit of "at most one working day" since a few years ago. Which, in case of weekends, may still be several days. Because computers dont work on weekends!
It's not great in DE for bank transfers. Either the account does not support sending SEPA instant or it's quite a large charge. Often savings accounts don't seem to be acceptable as destination accounts for SEPA instant.