Nah. Everything I've read about hallucinogens says dose doesn't change effect duration, only intensity. Drugs do affect people differently, so I wouldn't jump straight to saying they're exaggerating.
Also, 12 hours is definitely not short of LSD. I'd say it's the standard duration, with the peak lasting 7 hours. Longer trips can happen, at least to some people, but the default assumption should be about half a day.
definitely not hyperbole. last time i took LSD i dropped at 5pm before going to dinner and ended up at a bread factory 15 miles away at 5am watching them run the big mixers. no idea how i got there just remember walking all night.