You don't need 16 banks to eliminate all risk. You need one bank and a treasurydirect account.
Anybody, including corporations and partnerships, can safely park excess cash at treasurydirect.gov. Buy short term treasuries and time the redemptions to coincide with next month's payrolls. The shortest bills are 4 weeks and they're paying like 4% right now.
I honestly don't understand why more people don't do it.
Treasurydirect is great and everything you say is true, but the poor user experience and the commonly reported difficulty involved in getting help if there is a problem make it more appropriate for personal finance than business, I would think.
More generally the approach of using a cash sweep account in conjunction with t-bills held with a custodian bank seems like pretty sane advice. I don't think I'd emphasize "one bank," but otherwise, sure.
Anybody, including corporations and partnerships, can safely park excess cash at treasurydirect.gov. Buy short term treasuries and time the redemptions to coincide with next month's payrolls. The shortest bills are 4 weeks and they're paying like 4% right now.
I honestly don't understand why more people don't do it.