If you get detected and they are equipped to vanish once more, enemies will look for you in pairs (a single watcher and a single seeker) and will remain a lot more suspicious going ahead. Which means that techniques like whistling to lure them in will only maximize their suspicion https://assassin-s-creed-shadows13579.angelinsblog.com/31622043/how-assassin-s-creed-shadows-can-save-you-time-stress-and-money