“The thing is that historically since the early 50s, .37 and .50 have the same record of calling recessions.”
According to fed data the only time it reached 0.5 was in 2020 and totally missed the 2000 and 2008 recessions only reaching 0.05.
OTOH, the rule was not designed to predict recession. I was designed to signal when to start fed stimulus.
https://fred.stlouisfed.org/graph/?graph_id=910571&rn=34