I gotta say, that's one of those Hints from Heloise things that actually doesn't work half the time.
Why? It presumes there will be a screw or nail on the stud you seek. Not always the case. And since strings don't hang upwards, you'd better hope there is a screw/nail ABOVE where you want.
It also presumes the screw/nail is centered on the stud. A crap shoot...it's just as likely to be 1/8" from the edge.
Then, you have to mess with string, too, which is its own PITA.
A stud finder locates the stud's edges/center. It fits in your pocket, no unraveling or winding back up. It works on any wooden stud...even horizontal wood pieces. At the very top, or very bottom, or anywhere in the twixt.
Before I sign off, a couple drops of oil will stop a squeaky hinge from squeaking!
Heloise.