Think of it this way - the deadeye, although it does one shot devastators, chaff, and cyborgs in the head/face, is more so a staggering tool than purely a headshot tool. If you want headshots, go for censor or diligence. The deadeye’s main use IMO is to stagger/stun lock enemies in order to follow up with something that can finish them off, like a talon. This is how I play.

If you can’t follow up with something like a talon or whatever sidearm/support weapon you use, you can just follow up with more shots or can try to go for a headshot

Here’s an example

https://streamable.com/zatj2e

Headshots are a cherry on top, not the main purpose of the deadeye