This is the pro-tip, a Bahn Card 25 reimburses itself in 2-3 trips and trains booked 6 weeks in advance (which is what I do for airplanes) or even 3-4 weeks in advances are inexpensive (like 30€ for a Hamburg Dammtor -Frankfurt HbF which is way more comfortable than going to both airports).
One thing I despise about trains in Germany and France is that the experience still feels way too old school. What happens when something is delayed or when a connection has an issue makes you feel back in the eighties. The Deutsche Bahn applications are a great way to see that, it's confused and overly complicated. I wish the UX of apps/websites like https://www.trainline.eu/ would be the standard by now.