I have walked for 18 days continually in Leh and Ladakh but that was in the past but I don't think I would be able to repeat that trip now because a trip like that would be too much for me now. I mostly do 2-3 days' trip now in easier but interesting areas with lots of stays on the way. I have just completed an overnight walking trip for charity that was only 28 km but we did it in almost 2 days.
18 days!!! How many KM you walked for? That's really amazing. My highest is only 3 to 4 days in hiking. If I talk about walking on normal place then I have went for 5 to 6 days walking for going to particular place. But not more than that. 18 days, I don't think I can go for such long route.
So as it was Leh and Ladakh, I am sure the road was not kind of plain highway, I mean you should have face lots of up and down.