I agree to not boil the chicken in water to avoid a bland result. Additional salt is not necessary usually because of the saltiness from the soy sauce. Although if you use a Filipino brand soy sauce (ie: Silver Swan) it tends to be less salty than your regular Kikkoman soy sauce.
I marinated the chicken with the soy, vinegar, garlic, peppercorns, bay leaves for an hour. We never boil it in water (chicken will lose its taste) Then simmer in low fire adding just enough water to cover chicken. No more salt, just 1t sugar and let it simmer for 30- 45 minutes till flavor concentrates. Sometimes we melt 1/2 c butter and saute the cooked chicken pieces in it and pour the entire adobo sauce to it, at least this is how my kids like it. good comfort food.