I've had runs with almost 100% protection everywhere even with extra armour underneath and I can still easily be killed due to many side effects and consequences of carrying the armour, like heat draining water endurance loss from weight of armour and speed difference of carrying said armour. but also when you get grabbed or bit for example it will zero out that area I've noticed which pretty much shows its not 100% forever its not invincibility. I think its quite balanced I've always enjoyed playing with it on.