According to the original bullet journal folks what I’m about to show you don’t count as collections but it’s still what I call them.
“Sometimes you’ll have notes and tasks that are related by a common theme or purpose. Rather than having all these related entries scattered across your Bullet Journal, simply create a Collection Module. Collection Modules, or Collections, are great for organizing specific lists (shopping list, reading lists etc), classes, and projects.” Pulled from http://bulletjournal.com/collections/
My only theme is that these next ones can last thought the year potentially.
These are my monthly bills. I’ve only listed them out though August. Each time they’re paid I’ll cross out a box with that color. I used to make countless spreadsheets for this. The bottom are gift subscriptions I’ve purchased, this reminds me when to cancel them as well.