DST's not really all that useful at either latitudes where the day length is relatively uniform throughout the year nor at latitudes that vary between more light than you know what to do with and dark in morning and evening no matter what.
It's really primarily useful when you have enough light for long summer evenings and winter days that are short but are still long enough that it makes sense to fine-tune sunrise and sunset relative to normal work and school times.
It's really primarily useful when you have enough light for long summer evenings and winter days that are short but are still long enough that it makes sense to fine-tune sunrise and sunset relative to normal work and school times.