The faster ones that only need 4h are indeed going only three times a day but there is a connection every hour that takes 4.5h (on workdays from 6 am to 7 pm).

The faster ones that only need 4h are indeed going only three times a day but there is a connection every hour that takes 4.5h (on workdays from 6 am to 7 pm). Seems fine, I think? (Source: www.bahn.de, the official website of Deutsche Bahn)