Plein air, while not a main aesthetic focus of my art, has played a vital role in the collection of ideas and education in landscape and light.
Under regular conditions I have only a couple hours to complete a painting while working "en plein air." soon the light has completely changed, rendering any more effort relatively ineffective.
Plein air forces me to a strict time schedule. It challenges me to work faster, with more effectiveness per brush stroke.
I use photography and a studio space, but the lessons learned while painting on location have been essential in the formation of my most successful pieces.