I see many different tummy tuck scars. Some are horizontal, others are shaped like a "V" or "U". Why are scars cut that way?

I see many different Tummy Tuck scars, some are Horizontal and others are shaped like a "V" or "U". Why are some scars located lower and others are higher? Why would a doctor make an incision a certain way? Example: "V" or "U" shape or horizontal Does making an incision a certain way pose a health risk?
