Utilize your financial knowledge, give your answer or opinion to the input question or subject . Answer format is not limited.

Why does it seem unnecessary to fully save for irregular periodic expenses?
Another way of explaining the puzzling balance: Right after a particular bill is paid, you have $0 saved to pay that bill the next time.  Just before the bill is next due, you wisely have the whole amount saved;  that's the purpose of the whole process.  So, for that bill, on average over time, you'll have one-half that upcoming bill in the account. But the same argument holds for every one of the upcoming bills.  So, for a large number of bills, with varying sizes and times between occurrence, the average amount in the account will be approximately one-half of the total amount of all the bills that you're saving for.