With respect to sunlight hours, wouldn't this technique depend a lot on timing (e.g. winter vs. summer) and latitude? I mean, it wouldn't seem to be of much use

With respect to sunlight hours, wouldn't this technique depend a lot on timing (e.g. winter vs. summer) and latitude? I mean, it wouldn't seem to be of much use in say northern Alaska during the summer where daylight nears 24 hours or in winter where you're in the dark much of the time.