a pellet smoker and have a temp alarm you could go straight overnight and rest all day. All the good bbq joints rest this way for at least 10 hours. I only go longer so i'm not up in the middle of the night and i've tested my oven to make sure it doesn't over temp.

IMO it's the most consistent way to improve your brisket results (IE, good to great, mediocre to good)

Adding tallow (goldee's method) vs. no tallow doesn't seem to change the result enough for me to do it consistently