(Sorry non-US/UK dopers, this question might not apply to you)
OK, the clocks have just gone back. We’re (give or take) 2 months before the winter solstice. 3 months (in the UK, British Summer Time begins) or 4 months (in the US, Daylight Saving Time begins) after the solstice, the clocks will go forward again.
BST/DST are intimately connected with day length.
Day length is directly related to the number of days from the solstice - you get the same length of day 60 days before or after the solstice.
So why aren’t the start and end of BST/DST symmetrically positioned around the solstice? I.e. why don’t the clocks go forward at the end of February?