The link below is an excerpt from a book written by a British journalist. Even those not in metaphysics believe that the
sun time is more fitting for humans than the clock time. And since birth chart reading systems intend to embody human energetic cycles, should these systems not use solar time?
https://www.theguardian.com/news/2019/jan/11/watching-the-sun-not-the-clock-sleep-body-clocks-daylight-saving-timeAnd here is an extract from that link, my comments are in blue:
By moving the clocks forwards each spring and backwards each autumn, we are creating a form of “social jetlag”, to use the term coined by the German chronobiologist Till Roenneberg to describe the gap between our individual body clock and the external clocks and timings that rule our lives.
By using the solar time, we take that "jetlag" away 
This all goes to highlight a central point: our biology is tethered to the sun, yet the clocks society uses to keep time are influenced by a tangled web of political and historical factors.
Exactly! Moreover, the latter factors change arbitrarily, and why should a system like birth chart reading be dictated by them?
Take Germany as an example. At its widest point, the country extends across nine degrees of longitude, and the sun takes four minutes to pass over each of them, which means that the sun rises 36 minutes earlier at its eastern border than at its western one. In a country with the same time zone – and the same TV and radio shows, school start times, and work culture – you might expect that everyone would rise at more or less the same time, but Roenneberg has demonstrated that people’s chronotype – their innate propensity to sleep at a particular time – is shackled to sunrise.
We also take into account this longitude difference. In solar time adjustment, one degree of longitude equals four minutes.
On average, Germans wake up four minutes later for every degree of longitude you travel west, meaning that those in the extreme east rise 36 minutes earlier, on average, than those living in the extreme west of the country. A similar pattern has been documented in the US, where those living on the eastern edge of its time zones get up earlier than those on the western edge, where the sun rises later.
Basically, anywhere in the world, not only Germany and the US...
