depends on how busy your airport is,
take KORD for example, when all runways are active you get much better traffic flow,
the line up for a runway in the default airport (only 2) goes back many miles
some airports are not quite as good but most airports work very well when the non parallel runways are active, gives you a better traffic flow if your AI is maxed out
Rays airports and mine give you the choice of either
Craig