what does "how long did it take you to paint this" mean?

this stage of the painting is "about" 16 hrs of working the surface later than the last entry on it>>>

my mother used to tell my two brothers and I she wanted us to "sit enjoying the Sunday meal before us as long as it took her to prepare the meal". If she had said "as long as she spent enjoying preparing the meal before us" it may have had a different effect. She did tell us that because she worked all week and we were doing our thing it gave us the opportunity to catch up with each other. Meanwhile, "don't talk with your mouthful."