I definitely haven't for the things I'm working on. Good enough is good enough.
edit: Thinking about it, that's not true. I was dealing with some hot code running on some MIPS architecture stuff a while back and the compiler's generated ASM was merely "okay", for the standard library. Alternative libraries with hand-rolled ASM ran significantly faster and we were going to leverage those, when another team came up with architectural changes that allowed us to take that away from the MIPS part of the stack.
I used to work on compilers and run-time libraries for embedded systems; our preference when we sub-optimally compiled the standard library was to teach the compiler how to generate the optimal code :).
edit: Thinking about it, that's not true. I was dealing with some hot code running on some MIPS architecture stuff a while back and the compiler's generated ASM was merely "okay", for the standard library. Alternative libraries with hand-rolled ASM ran significantly faster and we were going to leverage those, when another team came up with architectural changes that allowed us to take that away from the MIPS part of the stack.