There is a small negative side effect for not handling fractional nanoseconds.
For example, if you use the step instance method with a step value of 1/7th, the final yielded object will show up as a different date because the object will represent the final nanosecond of today's date instead of the first nanosecond of tomorrow's date.
This is because 1/7 of a day includes fractional nanoseconds, which get lost at each step.