Runways can be repaired much faster than that. It was one of the tasks my army unit did. Depending on the damage it might take hours. I’m sure things have gotten quicker over the last 35 years.
http://www.independent.co.uk/news/world/middle-east/syrian-planes-shayrat-air-base-homes-us-air-strikes-syrian-observatory-human-rights-bashar-al-assad-a7673511.html