NCIS during 2016 had about 18 minutes of ads for every 1 hour episode. During 2003 NCIS had about 16 minutes of ads per episode.
Those extra few minutes over a 23-episode season add up to an additional 46 minutes of ads. If you watched a typical 23-episode season of NCIS today you would watch about 414 minutes worth of ads or almost 7 hours.