After moving to a sunny place in the country I noticed how it affected my mood, so I think that every scheme to add natural light to our day is great for mental health. That's why stripping DST in Europe is in my opinion unfortunate.
Besides, summer isn't the time when sunlight is lacking. Winter is when people get vitamin D depressed, and no time change is going to fix that for northern countries.
DST is pointless and antiquated.
Because that's the easier method for society en masse to change 2 times per year. E.g. Some businesses have their opening hours painted on glass windows[1] so repainting them to say 8am-4pm instead of 9am-5pm is more complicated.
That's just a single example. I mentioned some others in a previous comment: https://news.ycombinator.com/item?id=11277093
[1] https://www.google.com/search?q=store+opening+closing+times+...
8am-4pm (2nd Sunday in March - 1st Sunday in November)
9am-5pm (1st Sunday in November - 2nd Sunday in March)
In fact, many business already use this technique successfully to display different opening hours for different days of the week.
Adding calendar qualifications like that to the times makes it even more complicated. To use another commenter's example about "valid hours of parking" printed on narrow street signs, there's no space to append long conditional text (like your suggested verbiage) to the times.
Also, the DST change date isn't stable. Over the years, the DST date boundaries have changed: from the last week in April -- then to first week in April -- then to March. The DST rules may further be refined to be always or never.
Did you look at my link to my previous message? The business hours on the window was only one example of complexity.
If we just change so we do all of these things an hour earlier in summer we either have to change a whole bunch of signs and other printed material twice a year, or we just have to remember that we need to mentally take an hour off the printed time during that time of year.
The former would be a major hassle and possibly an expensive one, and the later would confuse a lot of people for days or weeks after the switches.
Clocks, on the other hand, are designed to be changed.
If we want things to start an hour earlier in summer, and we want that to apply to everything, than implementing that by moving the clocks an hour forward is easier, cheaper, and less confusing.
The main hassle with changing the clocks is that there are so many of the damn things, although I think we may be getting past that.
(I say this is the main hassle, rather than the hassle of dealing with biological rhythms getting messed up for a while around the time changes because this post is about how, if we are going to have DST, it should be implemented--change schedules or change clocks. The biology thing is the same under both, so is not relevant in this comment)
At one time, say before the 1970s, it wasn't much of an issue because we didn't actually have all that many clocks. A typical family might have wall clocks in the kitchen and living room, table top alarm clocks in the bedrooms, and watches.
It was in the '70s and '80s that clocks started appearing everywhere, and worse, no two seemed to have the same mechanism for setting them and the mechanisms were usually almost impossible to figure out without the instructions. DST changing could be a frustrating evening of alternating trying to guess how to set a clock and searching through every place you might have left the manual.
But now, although everything still has a clock whether it needs it or not, those clocks are more and more likely to be self-setting. I think I have 15 clocks in my house and garage right now, and only 3 of them did not handle this morning's return to PST from PDT automatically. (And all three are or are in old things that if bought today probably would automatically handle the time change).
I have certainly seen hours of operation signs with separate summer and other hours -- they generally also indicate when they think summer begins and ends. Even if you did change the hours twice a year, that allows you to adjust for changing demand as well -- you don't always need to keep doing what has always been done.
I personally don't think parking and lane restriction hours are that sensitive, just set them to cover the full range of high traffic times.
Most of your self setting equipment is likely not to adjust to changing dst dates when next we add more days to DST.
So today daylight in Warsaw was 6:36-16:01, and in Madrid it's 7:47-18:08.
If people really cared about daylight saving - they should use the correct timezone in the first place and then worry about changing time.
Personally, here in the UK I'd like to see daylight saving time abolished, but we should stay permanently in summer time. In winter the sun is usually up well before I am, but in the evening it gets dark far too early.
We tried that for a couple of years at the start of the 1970's... Clearly it didn't last.
Flexible schedule of programmers is more of an exception then norm.