I think Supertape is made by TrueTape, not Walker, unless it's another type of tape from Walker you're using.
I use 1 inch wide Supertape on the back and sides of my system (a hyribd of thin skin but with Swiss lace for the hairline). I can easily go a month between attachments and wash as much as I want and the Supertape holds extremely tight.
Supertape isn't designed for the hairline (it's too thick) so I use Ghost Bond Platinum adhesive glue for that. I redo the hairline maybe once or twice a week, which takes 10 to 15 mins max.
If the tape or glue is breaking down when washing, try washing with cooler or even cold water and be gentler when washing (don't rub your hair system and shampoo in too vigourously). I that doesn't work, try different tapes and glues until you get something that holds better. Or wash the hair system less frequently and/or for less time (hair systems don't need to washed as much as bio hair because they don't absorb the oils from the scalp and become greasy. They still need to be washed from time to time, though, and that frequency will vary).