@xris That is slightly different and is a source of another line of rants of mine.

First of all, when you are dealing with past events, they are known and are not estimates. Reporting them with both precision and accuracy is desirable. Excessive precision is quirky, but not wrong; reporting an estimate of a future event with false precision is wrong.

OTOH reporting a past event with poor approximation invariably annoying and often wrong (both in its model and its implementation).

@mrotteveel @bellinghman My original posting covers that: that is why you communicate 10:00–15:00. Not only is the range more accurate, but you will also receive fewer complaints than 09:50–14:45.

(And yes, there is a small psychological trick in here that is worth knowing, and for that and other reasons it is better.)

@mrotteveel The probability of arrival between 09:50 and 10:00 is comparable to that of 09:30 and 09:50, so perhaps they should round down. Then again, the probability of arrival between 09:30 and 09:50 is...

"You're delivery will arrive today (probably)" covers, I think, most eventualities.

Received a message telling me to expect a delivery "between 09:50am and 2:45pm". To their credit, they avoided quoting the estimated range to the minute (or to the second!), but the implication of quoting such limits to a precision of 5 minutes is nonsense given that the window of uncertainty is 5 hours.

When developing software systems, understand your domain and understand your users. Your users are human, so go with "between 10am and 3pm" to sound like you know what you're doing.