If you carefully look at each word instead of mistaking the capital B for an L, failing to recognize the first word, and giving up in frustration, you can pick out common words like die or der and then slowly expand from there. It helps that one of the longest words in the text is Sütterlinschrift itself, which gives you quite a few letters. Once you have most of the alphabet deciphered, your internal language model takes over and it's smooth sailing from there. It definitely takes quite a bit of getting used to, but less so than e.g. Yiddish written in Hebrew script.

I second this. As someone who still learned "Schreibschrift" in school, I have a tiny bit of a head start but a lot of letters changed or at least changed in style drastically but I can reverse-engineer as you described.