There were occasions that I was asked how I bullet journal in a ring binder. It is pretty simple, just imagine your notebooks has rings. I have been in this system for the longest time compared to other systems.
What made me choose the ring binder? Flexibility in pages and sturdiness of the cover. It is cheaper in the long run than buying a bounded notebook with only 100 sheets, archive when done, and go get a new notebook again. Some information that you may still want to use is still in that bounded notebook, unless you want to tear it off or re-write to your new notebook so you can carry it with you again. With ring binders, I can just refill the sheets in a less expensive price. I can keep the sheets that I still have use and archive the not needed ones.
I reserve my bounded notebooks for art collection and memory keeping, but for planning, BuJo and ring binders are the items for me. So here are the basics in a BuJo that I use in my ring binder.