No, not for any extended period of time except to allow you to sleep in to a normal hour before chopping her down.
Convenience is a good reason. You don't want it photosynthesizing (a real word?) right before you harvest. You don't want those processses taking place, if you can avoid it before harvest (if not a word, lol). Same reason you dry your buds in the dark -- they are still alive! You don't want photosynthesis and other light-dependent processes taking place.
It's not important to prevent them for 24-36 hours for any reason.
i just set the timer to off the night before, and i harvest when i wake up.
If you observe more trichomes due to leaving it in the dark like this, it's not because it was dark.. it's because your lights are evaporating trichomes faster than they are created, lol. This is a prime example of the pitfalls of anecdotal evidence.