I do the string thing with a piece of waxed paper (grease proof for the Aussies
folded in 1/8's to have lines to follow for placing applique. To do that with this ruler the string would also have to cross at the halves.
I guess if you were only going to make, was it 22" or 24" blocks and you didn't have any other rulers it would be ok but any ruler you can only use for one thing seems silly to me. I mean, you wouldn't use it to cut strips. It doesn't look like you can leave out sections to make the ruler smaller.
I have both sets of her perfect circles, and I've heard her scissors praised to the roof. But this ruler. Not for me, and who keeps their rulers in a box? Mine hang on the wall for quick access.