Update: Since posting, I got to 40 twice and successfully caught a shiny Flabebe and a shiny Weedle. I no longer care as much about learning what rules do and don't apply, but for anyone that's curious, for both of those successful chains I ignored the "don't go to patches when an adjacent patch is also shaking" rule and the "only go for a patch when you can see five shaking" rule.
If anyone still wants to discuss the ins and outs of this method (or any other shiny catching method), I'm always happy to talk about that kind of thing.
If anyone still wants to discuss the ins and outs of this method (or any other shiny catching method), I'm always happy to talk about that kind of thing.