> Your reasoning is so far off. Banks don’t control how long it takes to move money, the fed does. Move money between accounts at the same bank, money transfer is instant.
Banks can be pretty silly with accounts at the same bank, too.
A friend of mine finished a contract job at a major defense contractor, which had a lump sum payment at the end. The company wrote him a large check, drawn on their account at the local branch of a major bank.
What he wanted to do was (1) open a checking account at that bank, (2) deposit about 95% of the check in that new account, and (3) take the remaining 5% as cash, for first and last month's rent at an apartment he wanted to rent that afternoon.
The bank could not do that. Even though the check was drawn on an account at that branch, they said it would still take three days to clear, so he would have to wait for the cash.
Finally, he ended up going to a teller and asking to cash the check. That, of course, worked, although it was a big enough check that it apparently triggered some safeguards that required getting a couple of levels of management above the teller involved, and so it took about an hour for them to actually hand him the cash.
He then took his cash, set aside 5% for getting that apartment he wanted, and took the remaining 95% back to the new accounts desk, and said "I want to open a checking count here, and deposit this cash".