Krystal ended the experiment prematurely after finding response times suffered. On Monday, its busiest day, the team was only 50 per cent staffed.
To smooth the move back to five days, technical support staff can finish an hour earlier in the evening with a 30-minute lunch break, reducing their working week to 37.5 hours from 40.
Others have reported better results.
More than 60 UK organisations took part in a four-day week trial last year. Of those, 18 adopted the policy permanently. A further 38 extended the experiment, reporting that revenues had remained broadly the same over the initial test period.
Most participants were from the marketing, advertising and professional services industries where working hours are easily reshuffled. Manufacturing firms would find it difficult to deliver the 25 per cent improvement required on other days to maintain productivity.
Unilever, which offered separate four-day week trials in Australia and New Zealand, did not include factory staff.
Interpretations can also differ. In the UK case, working hours declined on average from 38 to 34 — technically a half day not a full day. In Belgium, where employees have the right to ask for a four-day week, this means compressing their hours rather than cutting them.
A real four-day week is likely to remain an exceptional perk rather than the norm for most workers.
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