I think hex is superior to both as it’s way harder to strip than a torx and it has 50% more options for starting angle than a robertson, which comes in handy when you can only get at the bolt head from a right angle, while being almost nearly as grippy and strip-resistant. Plus it’s presumably simpler to machine than a torx star.
The biggest problem I have with hex drives is that there are far too many sizes, (in multiple systems!) meaning you have to carry dozens of bits, and using a size that’s just a little too small creates a huge strip risk.
Robertson and Torx both use a comparatively limited number of sizes, which makes the logistics way easier.
Even just counting metric there are far too many sizes of hex bits. Adding inch sizes further complicates things, and as you say, the similarly of some of them to their metric counterparts isn’t helping; is 5/32 close enough to 4mm to not break things? Who knows!
With that said, torx is really no picnic either. T6, 8, 10, 15, 20, 25, 27, 30, and 40 all seem to be in relatively common use, and I’m not sure they all need to be. Not to mention the (relatively common) security variants of at least the 10 through 40.
I think #1 - #4 square are the only ones I’ve ever seen in the wild, though I’m informed security versions of at least #2 - #4 exist too.
I think hex is superior to both as it’s way harder to strip than a torx and it has 50% more options for starting angle than a robertson, which comes in handy when you can only get at the bolt head from a right angle, while being almost nearly as grippy and strip-resistant. Plus it’s presumably simpler to machine than a torx star.
The biggest problem I have with hex drives is that there are far too many sizes, (in multiple systems!) meaning you have to carry dozens of bits, and using a size that’s just a little too small creates a huge strip risk.
Robertson and Torx both use a comparatively limited number of sizes, which makes the logistics way easier.
Even just counting metric there are far too many sizes of hex bits. Adding inch sizes further complicates things, and as you say, the similarly of some of them to their metric counterparts isn’t helping; is 5/32 close enough to 4mm to not break things? Who knows!
With that said, torx is really no picnic either. T6, 8, 10, 15, 20, 25, 27, 30, and 40 all seem to be in relatively common use, and I’m not sure they all need to be. Not to mention the (relatively common) security variants of at least the 10 through 40.
I think #1 - #4 square are the only ones I’ve ever seen in the wild, though I’m informed security versions of at least #2 - #4 exist too.