how to better use deadeye's called shot and critical weakness

1.called shot is a new way to make player could automatically mark enemy, but it have a 5S cd, and I found it can't link less duration or increase cooldown recovery.
could we have other way to short the 5S? or could we have way to create a enemy that could be hit and be marked.

2. critical weakness is a powerful debuff but it could only stack 5 once and its duration is only 4s,
the sniper mark have 6S cd and called shot have 5s, it would stack over 5 if we can't find other way to increase the debuff's duration or increase called shot/mark's cooldown recovery.
are there enough resource to do it?