I had about 51% of ZBLL learned at one point before I got bored and stopped. My advice:
- Use a virtual cube. Scrambling takes time, and you can get in
much more practice without it. Plus, if you set out to practice x cases, you'll be able to get through them much quicker, helping keep motivation up. Personally, I connected a Giiker i3S smart cube to
Tao Yu's trainer, and found that this worked very well.
- Practice every day. You shouldn't be going more than ~36 hours without a practice session. Practice individual sets you struggle with, or practice all your sets at once. Just get in a lot of practice or you'll start forgetting
fast.
- Don't learn sets too fast. I would learn an entire COLL set at a time, then drill a bunch before learning another. Sometimes I got down 24 cases in a day, but as you learn more and more ZBLL, you really need to slow down as you go. Once you learn an entire ZBLL set, you have to practice a
bunch before you should start on the next one. Trust me, it's easier than you think to forget cases you think you have down.
- When doing timed solves, actually do ZBLL when cases you know come up. It'll slow down your time, but it's important to get used to using your cases for real. If a case you know comes up and you think "ah I know this one, but I want a fast time so I'll just do OLL/PLL", then you'll never actually switch.
Biggest thing to remember is that if you're learning ZBLL/ZB because you think it'll make you fast, forget it and practice F2L or something else. It
can improve your times, but learning ZBLL is only going to be important if you're already like sub-8. There's better ways to improve your times faster and more easily. But learning ZBLL can be super fun and satisfying—that's why I tried to do it, and I think it's a perfectly acceptable reason to do so.