Estimates are difficult for developers and product owners

The unique thing about estimates in software engineering is that if you do it right, projects should be impossible to estimate!

Tasks that are easiest to estimate are tasks that are predictable, and repetitive. If I ask you how long it'll take to add a new database field, and you've added a new database field 100s of times in the past and each time they take 1 day, your estimate for it is going to be very spot-on.

But in the software world, predictable and repetitive tasks are also the kinds of tasks that are most easily automated, which means the time it takes to perform those tasks should asymptotically approach 0.

But if the predictable tasks take 0 time, how long a project takes will be dominated by the novel, unpredictable parts.

That's why software estimates are very hard to do.

I am in a project where we have to give estimates in hours and days.

Needless to say we always underestimate. Or overestimate. Best case we use the underestimated task as buffer for the more complex ones.

And it has been years.

Giving estimations based on complexity would at least give a clear picture.

I honestly don’t know what the PO and TL gains with this absurd obscenity.

The last director I had would ask "is it a day, a week, a month, or a year" he understood that's about as granular as it's possible to be.

And he really only used them in comparison to estimates for other tasks, not to set hard deadlines for anything.

This is essentially t-shirt sizing without all the baggage that comes from time. Your boss is trying to use the relative magnitude but it's inevitable that people will (at least internally) do math like "7 day tasks is the same as one week task", or worse over-rotate on the precision you get from day/week/month, or even worse immediately map to the calendar. Suggestion: don't use time.

If you pretend not to use time, everyone will do an implicit time mapping in their head anyway. I've never seen it go any other way.