Perk multi-activation
Some perks like hysteria and dark devotion are activated, and can't be reactivated while they are currently is use. I think this should be changed so that way the perk can be activated multiple times in a row.
Currently dark devotion only activates when the obsession loses a health state, which then remains active for 30 seconds. However if you hit the obsession again within those 30 seconds, the perk won't re-activate. If you damage the obsession, and then continue to chase them, the only part of the perk you are actually gaining value from is the lack of red stain and your aura being hidden. So if you hit the obsession with only 1 second of duration left, then you lose a whole second use of the perk. Hysteria is the same way, where you injure a healthy survivor the perk activates and that survivor is oblivious, but if you injure a different survivor, you are losing potential perk value.
There is one perk which allows for multi-activation, and that is gearhead. If you damage a survivor, and then damage a second survivor while the perk is in use, it will re-activate. Jolt also used to have a cooldown, so if you downed a second survivor during the cooldown, the perk wouldn't activate, but you removed the cooldown. I think that some perks would be too strong if they could activated multiple times in a row, however for some perks, which already have restrictions on when they activate, a limit on how many times in quick succession they can be activated holds them back too much.