its just a guide and of course there are horses for courses ,
many factors to consider too,
ideally one would have the timer changing like the days slowly decrease in hours ,
while also gradually drying out to mimick the natural setting ,
of course no one tends to do that and somethings are hard to mimick ,
honestly the sativas i have grown , depending on the planting time
were finished up to 2 months before the shortest day of 11/13 ,
maybe the days by the end were something like 11.5/12.5 ,
but the plants can tell when the season is waning so they act accordingly ,
(ie , it gets cooler ,, the ground dries out and therefore less food is available and the days shorten gradually... )
The first grow books I read talked about matching the decrease in daylight to natural fall by reducing the day hours every day until the end of bloom. I think that would be something very worthy of trying but would require more attention. But this would also provide longer day hours to mimic growing season.