Basic blender went bad (motor ran but spindle wasn’t rotating). I wanted to disassemble to see if it could be repaired. Three of the four screws were Phillips head. I had to cut the casing open in order to discover why I couldn’t unscrew the fourth. It was a slotted spanner.
I have a set of these that was part of a larger set of precision bits I was buying anyway. I’ve only ever used one of the security bits in like a decade of having them. I wouldn’t have bought the security bits alone.
That’s more than some sockets or crescent wrenches I have from sets. I don’t know that I’ve ever used an 11mm of either.