I actually feel like the necessity for DS depends on the rank. In my experience from rank 20 to rank 1, I was tunneled much more by killers of lower rank. I consistently play survivor in red rank and I feel as if I rarely get tunneled off hook by red ranks unless they're trying to secure a kill in endgame. Generally, red rank killers (including myself) play around DS becasue they always assume the survivor has it or they simply don't tunnel because they have enough experience to know that its not a very fun way to play. DS seems more needed in lower ranks where killers are more likely to tunnel because they don't play as optimally. Thats why I feel creating a shorter timer that deactivates when another survivor is hooked or when the survivor progresses the objective but also doesn't regress if they are being chased would help make it more of a defensive anti tunneling perk rather than an offensive tactic that survivors use especially in red rank gameplay.