Hack, very accurate assesment. I had a customer with a 71 Vert that another shop had covered up the rust and charged him for a restoration. Painted and everything. I pryed a huge ball of seam sealer out of the back of the passenger side rocker. I don't remember how many days I had in it, but replaceing that rocker (all of it-front to back) was a big job with lots of bracing. A huge production shop may have or even keep jigs they fabricate, but I made it as I went with one inch square tubing. With the vert there was a ton of bracing to pull a rocker. I would bet 90 hours was for both sides too. 40 hrs is a solid week non stop. I can replace a lot of metal in 40 straight hours.
Duke, what you take apart is up to you. Unless its some rare car, you can cut it apart just about anywhere you want and replace the sections that are rusted. It would be perferable to replace the rocker as a single part though. THe rear inner will be a lot of work to get at but is also probably te most rusted...