Dude. I don’t know what benchmarks ARMs are based on these days, but I doubt they’re going to use a rate that hasn’t changed in 6 fucking years. We used to use Libor and that was set either daily or weekly I think - whatever the practice was back in the 80’s.
Beyond that, what you pointed me to is based on the fed funds rate which is only for emergency borrowing. And by the way, there are 2 fed funds rates - what the fed charges and what banks charge each other. The first one doesn’t reflect market conditions - at least not in real time.
So I don’t know if you really understand any of this, but I’m starting to think not.