Part-hours

Why A Part-Hour Gap Is Harder To Schedule

The shared stretch no longer starts on the hour, and everything built on hourly slots loses a slot. The loss exceeds the offset that caused it.

A gap of two hours leaves six shared hours beginning on the hour. A gap of two and a quarter leaves five and three quarters, beginning at a quarter past.

The overlap has shrunk by fifteen minutes. The number of hour-long slots inside it has shrunk by one, which is a loss of sixty minutes of schedulable time rather than fifteen.

Where a schedule hides handoffs between specialists, project time insights for distributed teams can add project-time context while quality remains a separate human assessment. A useful external reference for the surrounding topic is Google Calendar.

Where the extra loss comes from

Hour-long slots begin on hour marks. A shared stretch beginning at a quarter past the hour cannot use the slot that began fifteen minutes earlier, because one end was not at work for the first quarter of it.

So the first usable slot is the next one, an hour later, and the forty-five minutes in between are real shared time that nothing is organised to occupy.

Gap	Shared	Begins	Whole hour-slots inside
2	6	on the hour	6
2 and a quarter	five and three quarters	quarter past	5
2 and a half	five and a half	half past	5
2 and three quarters	five and a quarter	quarter to	5
3	5	on the hour	5

Read the last column. All three part-hour offsets between two and three give the same number of usable hourly slots as a gap of three, despite having up to forty-five minutes more shared time.

A quarter of an hour of offset costs a quarter of an hour of overlap and a whole slot of capacity. The table reports the first loss and the calendar enforces the second.

Why this is not just pedantry about calendars

Because the calendar is where the decision actually gets made.

Nobody looks up the shared stretch and reasons about it as a continuous interval. Somebody opens a calendar, sees rows drawn at hour marks, and puts a meeting in one of them. The capacity of the arrangement, as experienced, is the number of those rows that both ends can attend — and that is the figure in the right-hand column, not the one in the middle.

The fix, and it is free

Express the shared stretch as a start and an end, not as a duration, and place commitments at its actual boundary rather than at the nearest hour mark.

A pair at a gap of two and a quarter whose overlap runs from a quarter past eleven can hold a meeting at a quarter past eleven. There is nothing wrong with a meeting at a quarter past eleven except that it is unusual, and unusual is cheaper than discarding forty-five minutes a day.

Where the schedule genuinely cannot bend — because other people are in the meeting, or the slot is institutional — then the arrangement has five usable hours and should be planned as having five, not five and three quarters.

Both ends of the stretch

The example above loses a slot at the start. If the finish is also off the hour, there is a second loss at the end, and the two are independent.

A shared stretch running from a quarter past ten to a quarter past four contains six hours and five whole hour-slots aligned to the hour. One slot is lost at the start, because the slot beginning at ten began before one end was at work. Another is lost at the end, because the slot beginning at four would finish after the overlap closes.

Six hours of overlap, four usable hourly slots. A third of the capacity has gone to alignment.

Stretch	Hours	Aligned hour-slots
ten to four	6	6
quarter past ten to four	five and three quarters	5
quarter past ten to quarter past four	6	5
half past ten to half past three	5	4

Why the loss is invisible in every summary

Because every table in this record, and every table anybody else produces about this subject, reports a duration.

A duration is the right thing to compute and the wrong thing to plan against, for the same reason a distance is the right thing to measure about a journey and the wrong thing to plan a train around. What matters is where the boundaries fall relative to whatever structure the day already has.

The structure in this case is the hour grid that calendars draw, and it is not negotiable for most people — not because it is right, but because everybody else is using it.

The overlap is a continuous interval and the working day is a grid. The usable part of an arrangement is the intersection of the two, and nothing reports it.

The general version

Two numbers describe a part-hour arrangement: how much is shared, and how much of it is reachable by whatever scheduling the organisation actually uses. The first is in this record. The second depends on the calendar, and the gap between them is the thing nobody measures.