Unusable, unreliable, incomprehensible.
Yes there was a usability threshold beyond which the basic radio functions were subsumed into always-on scanning.
On my radio I just punch-in the new frequency and hit Enter. A colleague with a new Uniden has to flap around with persuading the radio to stop 'scanning', enter the new frequency and be careful not to touch any keys because that will cause it to merrily abandon the frequency and go off scanning something else again...