I had not really thought about this idea until seeing this thread. I keep my “emergency cash” at an ordinary bank paying substantially zero% APR and for the amount in question, storing it elsewhere at ~4-5% APR would be worth the one–time hassle of opening & funding the account plus the occasional hassle of an interbank transfer one way or the other.
One thing I noticed in researching rates is that lots of places pay a 4-5% rate for straight up savings or for 1 year CDs, but a much lower rate for 2 or 3 year CDs, closer to 2 or 3%. The implication is that the high interest rates are a) a teaser / come-on to get you to sign up, and b) probably temporary so next year’s 1-year rates will be down near there today’s 2- or 3-year rates are.
Obviously the future trajectory of the Fed’s interest rate setting will influence / control how the outyears look. But the banks are clearly saying that they expect rates to drop again as soon as 12 months from now, and they don’t want to get caught paying folks like us excessive interest in 2024 & subsequent.
I have to say my attitude to moving my money around for a one-time windfall payment of $X this year is very different than my attitude to moving that same money to the same place for a reliable ongoing annual payment of $X every year.