The other reply was on the money (i.e. people would take different days), but also don't let the threat of "if everyone did it, something bad would happen" stop

The other reply was on the money (i.e. people would take different days), but also don't let the threat of "if everyone did it, something bad would happen" stop the immediate gains during such a transition. If your scenario was to happen, it would be 10 years at least, even with a quick change in habits. That's a long time before such problems come into play. Similar arguments are made against the FIRE (Financial Independence, Retire Early) movement - if everyone stopped buying things wouldn't the economy slow down? Sure, it probably would, but such large changes in behaviour take time, and adjustments would be made during that time if the trend continues.