When I went to school, the one I learned was Schulausgangsschrift https://commons.wikimedia.org/wiki/File:Schulausgangsschrift...
To me, the Sütterlin sample on Wikipedia is completely incomprehensible.
Generally, no. It is too confusing, since not only are many letters simply obtuse, some are mixed up with modern cursive writing. For instance, capital 'B' is pretty much exactly capital 'L', small 'h' is exactly 'f', small 'o' is 'v', and so on.
Fraktur for instance is much, much easier to read, since there is basically just one mix-up ('s'/'f'), it just takes some getting used to.
In Algebraic Number Theory it's quite common to use some kind of Fraktur-Alphabet for Symbols (Rings, Ideals, Groups,...). It's natural there to use some kind of Sütterlin for hand-writing and exercises. But I think to become really fluent, you have to dive very deep into Algebra... There are some letters you'll use a lot like p(rime), M(odule), G(roup), R(ing), A(lternating Group), S(ymmetric Group). I don't think I've read/written all available letters yet...
Could I make any useful guesses on the letters based on modern handwriting? Not at all. Many shapes are completely different, e.g. I knew about the long s, but never saw an e that looks like n or a B that looks like L before.
I get the sense, though, that especially in Bavaria it held on for a while even after WWII - very rarely you still see storefront signs written in it for flair, and somewhat more often you encounter subtle "Sütterlinisms" like having a lower half-arc above the cursive letter 'u' in the handwriting of older people and signage meant to evoke it.
What's interesting is that it's pretty much impossible for me to read if used for a non-German language. Sütterlin for English text? My brain cannot parse this at all - the script automatically flips my brain to German!
In a way, this could also be compared to the present-day use of katakana for loanwords and hiragana for native text in Japanese (which ironically only crystallised as a universal convention after WWII).
This is what is taught in german schools: https://de.wikipedia.org/wiki/Schreibschrift#/media/Datei:De...
The upper case X didn't have a horizontal line in my case, otherwise it's all pretty much the same as this 1941 doc.
They are remarkably different. Especially the lower-case letters, where around half are completely unrecognizable. Cursive Latin is arguably closer to cursive Greek than to Sütterlin.
Some lower-case letters straight changed meaning during the Sütterlin->Latin transition. d->v, e->n, ect.