Most strains like the natural weather. Afghanis love cold and definitely brings out a defense mechanism to protect the plant from cold. Which gives us reds and purples!!! 

So yeah also helps them get a warning that the season changes.

Now if we are talkin about an equatorial sativa there is no way in hell it is going to finish flowering before middle of February.

I had a strain Thai tanic that was in equatorial sativa it had a extremely long flowering . And was triggered into flowering by a change in humidity.

Some plants need it to finish flowering. Some hate it and it will burn leaves and buds. 

Always get Hardy strains. Afghanis love cold and definitely are mold and mildew resistance is high. Drought resistance as well and doesn't care about being overwatered. Great strains for beginners. 

Careful of misinformation. It's out there. Get Ed Rosenthal oaksterdam course book!!!!