5 hours is about right. Maybe even more if you have to deal with either PHX or LAS traffic.
Las Vegas and Phoenix are the only 2 cities of that size and that proximity in the country without a connecting freeway. It's ridiculous. As bad as it is now, it was way worse 10 years ago pre bridge and when US-93 was a 2 laner or almost the entire length between I-40 and US-60. At least now a lot of it is 4 lanes.