When I learned to sail, the Bowline (most often used knot), the Clove hitch, Round and two hitches these were all made to be important. Trust me the Rolling Hitch is a must know.
When you get an override on a winch, the rolling hitch will allow you to take the pressure off and fix it, when the bridle breaks at 3am, in snow being driven by 67kt winds (true story), the rolling hitch will allow you to tie on a temporary bridle side to get you through the dark night. When your stern to with anchor down and want to take the pressure off the windlass, the rolling hitch to the rescue (forget your bridle, it creates too many issues when you come to unwind it all).
And these are NOT the time to learn the most simple of knots. Maybe not the most used, but definitely the one that might just get you out of trouble.