I washed at 20-
had to, because at 20, I was at university in the halls of residence.
I even washed at 11, to relieve my hardworking mother of a big task she found sometimes burdensome.
Contact time, activity, temperature, and chemicals all have to be balanced for a good wash. Lee McMichael/Mac said it, Our darling Laundress says it, and I believe it. That should settle things.
Lawrence/Maytagbear