Just bought another socket set. (can never have too many tools.)
It came with 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19mm.
I cannot think of a time where I encountered a 7, 9, 11, or 16mm bolt. The only time I remember a 13mm was when I bought an aftermarket bolt to replace a factory and it came with an oddball 13mm head, when the original was a 14mm. The only time I've encountered a 15mm bolt was when working on a fluid pump doing HVAC work.
Where are people encountering these oddball sizes to motivate a tool company to offer them in their sets? When working on Jap cars, seems like 90% are 10, 12, 14, 17, 19 and 21.
