Ok this is one topic that bothers me for a very long time:
What part of the game decides how long a ward will be visible after it has been placed? Somtimes you can clearly see the ward when placed but you only have less than 1s to destroy it because it will go invisible otherwise. On the other hand there are situations where wards will be visible for more than 3s so that someone can destroy it with less than 1AS.
This is especially anyoing if you want to place a ward and the ward just don't want to disappear, so that the enemy knows the location of the ward and just can sweep it. But there are also this kind of situation where two people start attacking a newly placed ward but can't destroy it because it instantly disappears after the first attack.
Best of all is that there is no information how it works. It doesn't really matter if you see that ward when placed or if you instantly start attacking it. You can place a ward inside of a bush and it still will be visible for more than 2s or you can place a ward on the enemy and it will dissapear within 1s and vice versa.
It just feels inconsistent. I'd love to see a bit more documentation on this mechanic, because otherwise this is just a random luck factor.