It’s about 5% of the distance walking, but could be 25% of the time.
I enjoyed the Drumbeg road a lot last year. I was rested up, it was blazing sunshine, and I stopped in the store for a lot of food. If you are feeling on form, it is a great rolling cruse that section, an easy part of the course.
My guess is even doing it in 7 days would be not quite “fun” for most of us.
My feeling is that it is better to do it either as fast as you possibly can push yourself to do it, or to really tour it with lots of stops over 12 or more days.
7 days is still excellent going, and tough as hell. But to be honest, it is ‘finishing it’ that is the hard part, not how many days it takes. Dealing with the physical and mental strain is hard.