The question of interest is not merely "is this an HOV lane" but "can I use it at this time" and "is there anything the sign says other than the usual stuff tha

The question of interest is not merely "is this an HOV lane" but "can I use it at this time" and "is there anything the sign says other than the usual stuff that I would need to know". You're supposed to read all road signs, and only after reading can you be sure that their information is redundant.