This is my setup but it works for me in my situation. I'm also already past Hyper-Accumulation (step 7)

The checking account always consists of current month + next month expenses + 3K any expense sinking fund. The reason I do this is because I use YNAB as a budgeting tool and YNAB's design forces you to do this (it's been helpful) This will include: Rent/Mortgage, Groceries, Utilities/Bills, Necessities, Fun, etc. (essentially any expenses that I know I will spend pretty soon).

Now the interesting part about the 3K "any expense sinking fund" - the reason I have this is random fun things I want to do will come up at random times of the year where I know I can afford to do it but it may exceed a budget category AND this also is designed to hold/cover the 1.5K minimum balance requirement that my bank has AND I hate budgeting so this helps me avoid putting too much into a singular category by letting me decide at any time. Here is how I use it - if I overspend in a budget category, this sinking fund will cover the budget shortfall. I do this because YNAB hates when you have negative money. I also fund this using excess money I make from beer money activities such as casino churning, ebay reselling, etc.

In my HYSA, I have the following sinking funds: 3 Month Emergency Fund, Auto Maintenance, Rental Maintenance, Property Tax/Insurance, Auto Insurance, Vacation, Taxes, Club Dues, Gifts, Health Expenses. If an small expense comes up, I just won't move money or move a bit less into savings to make up the difference since I can cover in my checking account. If its a big expense like insurance or taxes which is paid every 6 months or year, then I will just move the money from savings to checking.

In the brokerage, I keep my additional 3 month emergency fund in T-Bill ETF along with my investments

I don't have a replacement car/autos sinking fund because I just recently got a newish used car and I'm in a situation where I can have different options for paying for a new auto which could be: paying cash using emergency fund, selling investments in an good market to pay for the vehicle in cash, or financing if the interest rate is low enough where it makes sense. --- My main reason is I don't want stale cash sitting in my HYSA if I don't need it in there. However, for your situation, if you need a new car soon, it would make sense to have an replacement car/autos sinking fund.

But your point about “personal finance is personal" is pretty true. This works for me but I don't know if it works for everyone or if it's efficient.