[analyst74]

Is your company requiring hour or even minute accuracy of the estimate?

In my whole professional life, I have not been put in such situation, even when working as consultant where we charge by the hour -- we simply estimate by week or day then multiply.

The art part of estimation is setting expectations, or more precisely, adding and justifying buffer time, and form an acceptable narrative when the schedule deviate from plan.

[timurlenk]

I mentioned that no greater precision than a day of work is required. The point of the question is not precision, but who and possibly how.