Why fewer operations on weekends? Why are there fewer air carrier operations on weekends? Looking at PHX data, we have the following annual trend that clearly shows a weekly drop of about 8% on weekends:


and when I average the data a strong weekly pattern is evident:


Is this simply telling us that most traffic is business related? Or is it, in part, that major cargo haulers don't work as much on weekends? As the charts show, we're talking about a 1200 vs 1000 daily operations difference.
Your data TELLS us that the airlines schedule fewer flights on the weekends, from which we can INFER that there is less demand for travel on those days.  (The numbers of cargo flights at PHX are dwarfed by the numbers of passenger flights there. The data at a major cargo hub like MEM or SDF might be different in that regard.)

To what extent that is driven by business travelers or leisure travel patterns, is beyond your data, and might even get into some fairly complex data and calculations that USAir and Southwest and others use to build their schedules.