I find from south Florida to Fairbanks takes us roughly 10 driving days as making 450 miles a day isn't a problem for us. A lot depends on a RVers age, health, enjoyment of driving, etc, as to how many days it takes. My BIL and his family, when living in Anderson Alaska, normally figured on about 50 hours to Bellingham Washington, which with 3 drivers, they would leave Anderson after work on a Friday and driving straight through would arrive in Bellingham on Sunday evening. Not my preferred way of travel but it worked for them. For many residents, going to/from Alaska by vehicle, they see the Alaska Hwy as just a long road to drive to get where they want to be, which is Outside in the Lower 48.
The quickest I have ever made the trip was Anchorage to the Houston Texas area in 6 days, averaging 800 miles a day approximately. I was solo in a car and driving 16 hours a day. When I got tired, I would pull over and sleep in the car for a few hours and hit the road again. No desire to ever do that again but was necessary that one time.
So if a person has multiple drivers, the trip can be made somewhat quickly. My wife doesn't care to drive on most trips but has driven the Alaska Hwy with our two pre-teen age daughters in our class C motorhome one trip. I flew down and met them in Colorado that summer after I got the work issues settled down to where I could leave