It turns out, of course, she knew what she was talking about. What’s doable at 60 or 120 wpm is another story when going towards 200 wpm. For me, certain -FN-based strokes are coming out like garbage even after practice. So the latest tweak to my writing has been changing the "even family" to outlines with easier strokes.
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I’m not saying the –FN stroke is not able to be mastered, but it’s going to take time. This is just somewhere to start, and I think this particular word family comes up enough to warrant simplifying. If it slows me down, practice it. If it doesn't improve, change it.
For more practice on the -FN stroke, check out Lady Steno's -FN and -MGS drill.