You are correct. In the age of electronic check clearing, unless you are banking at Fred Flintstone Saving & Loan or some other hopelessly behind-the-times institution, checks are clearned between financial institutions virtually instantaneously...most don't even bother to 'mail the paper'.
As for your your bank holding your funds for 5 days: This is known as the 'float'...aka stealing. Lots of banks do this unfortunately...in this day and age in which banks are eating bad mortgages left and right, they don't ;miss a trick to pickpocket a few extra pennies of revenue to make up for the losses. In this case, even though the check clears almost immediately and the bank knows there is no risk of eating a bad check, they are taking advantage of you by using your money for free for five days.
If you have a long-term relationship with the bank in question, it's time to use your leverage and sit down with the manager and have a long talk to avoid this in the future. That failing, it's obviously time for you to go shopping for a new bank, since your bank is clearly indicating to you that you are not a valued customer but instead fodder to be ripped off whenever the opportunity presents itself. .
3-5 days it really depending on who and where you are.
In today's world of electronics a check from anywhere can be cleared in one day. The law has been changed recently to allow banks to clear checks electronically without having to go through the federal deposit bank with the actual paper check. Some banks may still withhold funds for larger, out of town, checks for 10 days as they did years ago.