it probably depends on the temperature
i know either to high or low creates more yeast which is not as desirable as bacteria
sometimes its takes more time and patience when you leave it out instead of warming and then insulating, i know i tried to make counter top yogurt and when it didnt provide results in a week i stuck it in the refrigerator and another week later i had really tasty sour cream....go figure?
honestly these days i am lazy(and homeless!) and when i can i buy white mountain whole milk yogurt from the grocery. i know its NOT raw, but it does have live cultures and is really good quality, only whole milk and cultures, sold in glass, decent price, great company
i mix that with some okios kefir sour cream(admittedly not the best quality but really delicious), butter, raw beef liver and citrus juice or baked orange veggies, salt and munch on whatever greens, herbs, weeds i can thats my blood/bone healing energy drink, probably sounds gross but thats my intuitive meal