Tattwa durations and nighttime?

[sk4p]

Does each tattwa dominate for 24 minutes, period, the end, regardless of location or time of year?

If the cycle always starts at sunrise and is rigidly 24 minutes each until the next sunrise, then the final Prithivi is gonna get shortened a bit each night when the days are getting longer (earlier sunrise), and there should be a little "bonus" Akasha after the last Prithivi when the days are getting shorter (later sunrise). Is that the case?