I was high on a ladder painting my aunt's dairy barn when the bull approached. By his ears, he appeared to be on the verge of violent anger. I froze. He calmed down and went about his business. That barn was a lot of square feet, but I didn't know how to use a roller on an extension ladder. I've used brushes more than rollers because you need a place to put a roller pan and I've found brushes easier to clean than rollers. I still use brushes I bought in the early 1980s.
Loading a brush was easier from a plastic pail than a paint can, but I usually had to turn or walk a few steps to reload. To repaint a shed, I bought a pump-up sprayer. I sprayed with one hand while brushing it in with the other. The job went faster but I had to keep cleaning the nozzle.
There were other problems with brushing. In the time it took to apply half a gallon from a pail, some paints required stirring. To reduce running and dripping, paints have additives to speed thickening on exposure to air. Increasing viscosity could make it harder to spread the paint and get it into corners and cracks. Thickening could make it hard to clean brushes and other equipment.
I began ladling paint into a quart-sized plastic LLoyd's Barbecue tub. Suppose it took half a gallon to cover 200 square feet. Suppose it took an hour. That's how long the paint in the pail would have been stiffening when you finished. Instead, I might ladle a pint into the tub to do the first 50 square feet. I'd brush the excess out of the ladle, drop the ladle into water, and put the lid on the can. Holding the little tub in my other hand made reloading the brush much quicker than using a pail, whether I held the pail or set it down. The tub would be empty within 15 minutes. Not exposing more paint than I could use in 15 minutes meant more consistent viscosity and an easier cleanup.
I clean the mating surfaces of the rim and lid and apply a film of silicone grease. That way if I need the same paint ten years later, I can remove the lid without damage and the paint will still be good. I switched from ladles to syringes because a syringe is better for keeping the rim clean and it's easier to clean. Yesterday I wanted to prime 30 square feet, indoors and out. The lid came off easily. I mixed, cleaned the mixer with the brush, and dropped the mixer into the pail with enough water to keep the painty part wet. I have a vinyl tube on the syringe to pick up paint without getting the outside of the syringe wet. For that job, I estimated 10 oz, or 2 syringes. Some paint clung to the walls of the tube. I dropped the syringe into the pail so water would keep air out of the tube. I used a 24 oz Glad food storage container instead of the slightly larger barbecue tub. Painting didn't take long and cleanup took 2 or 3 minutes.
BULB 
!!@
I raced on Felts.
