As a sailor, the overhand knot is mostly useful to know as a cautionary tale. If you tie one in the lines on my boat, I might throw you overboard. Never tie a plain overhand knot. It jams up under load, and is near-impossible to untie. It also weakens the rope by crushing the fibers.
I have almost never encountered a situation where a regular double or triple knot didn't do the trick for whatever i needed. Interesting coolguide nonetheless
I learned knots growing up, and I find myself using two half hitches and a taut line hitch fairly often. Slip knots are great for quick releases. A clove hitch doesn't do too much on its own, but is great for starting a lashing, or wrapping around one post, as long as the other end will be tensioned with a taut line hitch or similar.