It refers to a specific time, usually when work or daylight is coming to an end.

Actual Timeframe

It's not just night; it can be the latter part of the afternoon.

Not Necessarily Night

It suggests a possible delay from the standard timetable or schedule.

It implies that the timing is inconvenient and may cause issues or inefficiency.

It highlights that the action taken may be less effective due to the timing.

Its idiomatic use often depends on context to convey urgency or wasted effort.