The dividers I have now are:
Daily: this is where I keep undated daily pages to use when my normal day gets too busy. This tab also doubles as a place to keep random current projects (for example, when I was in charge of planning a cookout for my sisters and our families. I kept the food list and to-do list here).
Weekly: my week on 2 pages section is the workhorse of my planner as I use it the most often. I am currently using an insert that has a notes section, a to-do list, a Monday thru Sunday layout, and a lined column where I am keeping up with my 31 Days schedule, bills due at a glance, my weekly menu, and a look at next week.
A-Z tabs: this is my notes section that works as a filing cabinet. Written on the inside of the tabs are random bits of information (I blogged about this on day 3) such as my hair color number or the air filter size. I use this section to keep up with inserts that don't need their own tab, medication list, a frequently used take out order, 2019 future dates - etc.
January - December tabs: Although I use a half size planner, these tabs are made for a Filofax - I think A5? They stick out a little farther than the rest of my tabs and make them easier to see and get to. I put them in the back so they don't cover my other tabs. I use month on 2 pages inserts
Use as many dividers as you want to, but I suggest using as few as necessary to make all the items in your planner easy to get to. Using a combination of A5 and Half size dividers helped me to do this. Be creative - it's your planner! Custom make it to fit your own needs!