Airless spraying is at least 10 times faster than a roller, and it makes a much better finish. If you don't have an airless pump and you are not a professional painter, you can hire one.
Part of the secret with efficient spray painting is the masking. You need to use a masking dispenser to do it quickly. 3M do them plus masking tape that you can still peel off weeks after it applied and you use a thin plastic film alongside. Remember that you only have to mask once, whereas you have to cut in each coat with a brush and roller.
Since you will be spraying water-based paint, the only mess that you make, is a small amount of dust that you can vac up after, so you need to close doors to other parts of the building and wear a cap, or better a cotton spray sock and a particle mask.
At the end of the job you chase out the paint in the machine and the hose with water, so there's little waste. It takes about 10 minutes to set up the sprayer and fill it with paint ready to spray, and about 20 minutes to clean it out and pack it in the van. How long does it take to get the roller working and clean out the cover at the end of the day?
Its not just the Americans that spray paint, but also the Germans and the Swiss, and... many painters on the Continent, but we are catching up although painters who do spray in this country, keep this weapon a secret and make lost of money.