Bugs like the ones you describe come down to timing.
But it's not like "the old days" where for a specific target, there was only 1 chip/clockspeed so devs simply relied on it for timing since an RTC was or not available, or too slow to access.
These days, it would be very hard to actually write code that relies on a specific clock-rate and work reliably. It's a lot easier and reliable to use the clock for time-sensitive stuff.
