I use measuring cups and spoons when I am writing recipes or when I want to duplicate a flavor that has been a winner in the past. Why mess with success?
In casual cooking, I eyeball it. I cook for three teen-age boys and a husband of 17 years most of the time. The only pressure I have is to make the food appear. Flavor is not so much an issue.
When I am in a hurry and still want "Mom's best dish" results, I use the old Justin Wilson method of measuring in the palm of my hand. When I cup my hand, I know where on my palm dry ingredients measure to. I can measure 1/4 tsp. to 1/4 cup with accuracy. I will measure in my hand for 1/2 cup but it is not as consistent. Yes, I have big hands.