Shift Length

Optimisers produce short shifts because they match demand precisely. The cost of that precision falls outside the model.

Why short shifts appear

A three-hour shift covers a lunch peak exactly.

Two of them cost less than one eight-hour shift.

And the labour percentage improves, which is the number being optimised.

What the model leaves out

Travel. A person travelling forty minutes each way for a three-hour shift spends a third of their working time unpaid and unrecognised.

Which means short shifts are declined, swapped away, or accepted by people with no alternative.

Handover. Two shifts require two handovers, and the first fifteen minutes of any shift are less productive.

Recruitment. A job composed of short shifts is harder to fill and harder to keep filled.

And in some jurisdictions a minimum shift length or reporting-time pay applies, which prices the practice directly.

The threshold that matters

Ask what the shortest shift worth travelling for is, at your site, given local transport.

It is usually four hours and sometimes more.

Anything below it is a shift you will struggle to fill and that will be first to be swapped or declined.

Set it as a floor and build around it.

Where short shifts do work

People who live nearby and want exactly those hours — students, second-jobbers, parents during school hours.

Who exist, and should be scheduled for them by preference rather than by allocation.

Which requires knowing who they are, and that is an availability conversation rather than an assumption.

The long end

Shifts beyond nine or ten hours have their own problems: fatigue, break feasibility, and rest before the next one.

And they concentrate coverage risk: one absence removes a whole day rather than half of one.

Check the distribution of shift lengths rather than the average, which hides both ends.

The measure

Shift length distribution, by site.

Decline and swap rate by shift length, which reveals the threshold empirically.

And fill rate on short shifts, which is usually the first place a staffing problem shows.

Find the threshold empirically

Rather than assuming it.

Decline and swap rates by shift length.

The point where they rise sharply is the shortest shift worth travelling for at your site, given local transport.

It is usually four hours and sometimes more.

Set it as a floor, and schedule anything shorter only for people who have asked for exactly those hours.

Connect policy to configuration

The choices in this note can be compared with this project connection. Enable only the data required for the stated purpose and confirm who can see and change it.

Independent reference

For a thematic point of reference, see HSE guidance. Its current material provides useful context beyond product documentation.