For CPU profiling, the rate of profiling is being set internally at start of the call and reset at the end of the call. So it goes like this

CPUProfiling() {
StartCPUProfile() // internally calls SetCPUProfileRate(100)
sleep(seconds)
StopCPUProfile () // internally calls SetCPUProfileRate(0)
}

On the other hand for mutex and block profiling, it expects us to set the block/fraction rate in our program before calling profiling.

My doubt is why mutex and block profiling have different behaviour ?
If we can set the rate any time then similar to cpu profiling, block/mutex profiling can also be implemented like
go tool pprof http://localhost:6060/debug/pprof/block?seconds=30&rate=1
Where internally we can call SetBlockProfileRate/SetMutexProfileFraction before starting profile and after profile interval (eg. 30 seconds) when profiling finishes then we can reset it to 0.

This different implementation made me question why is there a difference in the profiling technique, is it expected from us to set profile rate at the start of the program, if not then why is it not implemented similar to the cpu.