The theory material for the FAA IR states that you should always carry VFR charts in case you lose comms/nav and need to procede VFR
That suprises me because they put in a lot of time teaching and testing the exact lost comms procedure, where the flight is completed non-radio under
IFR.
The only time one would revert to VFR and stay VFR is where certain classes of emergency happened
while in VFR conditions.