Just came back from Asheville on that very route. They have made some strides on the section near Asheville but still needs a few more years. They have smoothed out some of the bone jarring sections. Seems it’s been going on forever. The construction between Chapin and Columbia on 26 can get slow and now is about the best time to go through as they are also about to start a decade long project to address the awful I20/I26/I126 interchange affectionately known as Malfunction Junction.
The only way I know to avoid all the work going on around Columbia involves back roads from I26 to I77 then to I20, or backroads from I26 to I20. All will be less stressful but longer. I start looking at going from Prosperity to Blythewood or Dentsville avoiding interstates. There just not a lot of bridges across the rivers.