what's good width and length of hair around the perimeter of the hair system?

[Fanjeera]

otherwise a fade or just very short sides and back are good look and for hiding it, but if the hair is too short, it doesn't hide the base anymore well enough. How wide of a strip of biological hair around the base is good to hide it, even if an accidental small lift happens? and how long hair?
and after that strip would be good to a fade and very short hair.
thanks!