Compressed hours
Compressed hours means someone works their usual hours over fewer days. A five-day week of 7.5 hours becomes four longer days, for example. The total is the point. The rota is how you write those longer days down.
How it looks on a week
There is no separate compressed-hours switch in Shiftbrook. You add the shifts you mean: four days of 9.5 hours, or three long days and the rest off, or whatever the agreement actually is. Each shift has a start, an end and a break. Publish them when the team should see them. The days with no shift are simply days with no shift.
A longer day is where the working time warnings matter. Saving a shift still saves it if the 17-week average would go over 48 hours, if there are fewer than 11 hours between shifts, or if the week has no 24-hour break. The warning is shown. Under 18, tighter limits apply when a date of birth is set. A compressed pattern can trip those warnings more easily than five short days. The warning does not redesign the pattern for you.
Holiday still follows the week they work
If the contracted week is four days, the 5.6 weeks of holiday are 5.6 of those four-day weeks, not an automatic 28 days. That is the same rule as any other part-time or full-time pattern: it is their week, multiplied by 5.6, capped at 28 days. Shiftbrook pro-rates from the allowance you set. It does not infer a compressed pattern from the shift lengths and rewrite the allowance overnight.
The break on a long day still has to be real. The company rule defaults to 20 minutes unpaid after more than 6 hours. On the clock, the minutes between Start break and End break are what come off the timesheet. A short break is flagged. The missing minutes are not invented to make a compressed day look compliant.
Sources
Shift patterns · Holiday accrual · Rotas · Shift hours calculator