I drive 12-14 hours straight fairly easily. However I think there should be limits. Drowsy driving is a killer and IMHO should be regulated. I have done 23 hours before. Not something I am proud or or would do again. ....but seemed fine doing.
Actually, in Texas, it regulated is for CDLs. Anybody know the weekly/daily limit? I think it is weekly and 75ish hours.
Probably 'safe' to drive up to 18 hours straight, once a week, with lots of coffee. You know yourself tho,,, if not drowsy than no problem.