China does something no other country does. In order to make holidays appear longer, Before Spring Festival, they force people to work the weekend, then give them 5 days off, then force them to work the next weekend before starting a normal 5 day workweek.
They call it a "5 day holiday" when you actually only get one extra day off.
because most people just take vacation on the weekend days anyway.
When people do work those weekend days, they do very little, show up late and leave early.
Because it forces people to use their leave days to take weekends off, which they normally get off for free.
This year, May 1 is a Tuesday - this holiday is just one day off. In order to make it more of an occasion, the Saturday before is considered a working day, and then you have off Sunday, Monday and Tuesday following.
You work 260 days in a row, and then have all your weekend days in a row: a 3 month paid vacation? No? Ok how about work 120 days straight, then 45 days holiday? Still don't like it? Hmm, we seem to be approaching the status quo. How about every month work the first 22 days, then be off for 8 or 9 in a row? This might be tolerable, but 22 days in a row is really a lot!
Beyond our current 5 on 2 off schedule, we could go to a mini-week - 2 or 3 days on, and 1 day off. Would this be better? Recovery-wise, it probably would be. But it'd be impossible to take 2-day trips.
Rest, recovery, and taking care of important stuff. But also, going out and getting hung over. At least with 2 day weekends, hung-over people waste one of their own days.
It kinda actually could be good to be able to give up 4 Saturdays and then take 4 extra days off in a row. Personally, variability would let you do a lot more travel. But it would be bad for the economy as a whole.
Are people so simple-minded that they just have to celebrate May 1 on that actual month & day? Yes, this is part of it. It just wouldn't feel "right" to celebrate it on another day.
It's the same reason there's such a huge jam-up around Spring Festival. Nobody wants to take off a week earlier and be home for the week leading up to the Festival - they only want to be there for the standard time: festival day plus a week after. In the US we don't have this - some people get home a week before christmas and leave the day after, others arrive that night and stay til new year's. That flexibility reduces the intensity of the load.
Of course, in the case of May 1st, this purity to the date ignores the fact that the solar calendar isn't even really traditional Chinese anyway, and just replaces the "pure" lunar calendar. It also ignores leap years shifting days around (up to 1 day off, depending on the year).
I have to admit, the idea of having a Sunday mood on a work day could be interesting - the same way having Monday morning mood on a holiday is a worthwhile experience to have occasionally. But the goal of the policy is probably just efficiency.
The gov't realized that people have to have long holidays for the traditional days off, but it didn't want to give the long holiday plus annual leave days for them, so they just force people to use leave or go unpaid to get the days off they want. The policy is possible in China because everything is part of the same system - there are no independent schools, public spaces, etc. - it's all locked together.