When planning your air travel inside Argentina, remember that in almost all cases, travelling between any two given cities will have to include a stop-over and/or change of plane in Buenos Aires.  Buenos Aires City Airport (AEP) is the only major hub for domestic air travel, so its almost unavoidable unless you travel on a charter or on a very small regional carrier (very few of which are today in operation). 

This makes domestic air-travel time a very consuming task.  Say you wanted to fly from El Calafate to Jujuy.  El Calafate is in Patagonia (in the south of the country), while Jujuy is a province well up in the north.  Since some destinations only have limited flights per day, a nightly stopover in Buenos Aires may be unavoidable just because you will arrive at AEP after the last flight of the day has already left.

Even if you could catch a same day flight, you may have to sit for a couple of hours at the airport.  Instead of this down time, it may be smarter to cut your Buenos Aires stay into sections, thereby better using your time for additional sightseeing, catching a Tango show that evening and then flying out to your next destination the following day.