Generally, as a rule of thumb, yes. Most airlines have ZEDs behind all other employees, eligibles, and buddies.

Couple exceptions I know of on United:
Star Alliance carriers generally fly at the same priority as United Express employees
Employees (not dependents) have the option to fly at a priority lower than ZEDs. It's a risky move, but if there's plenty of seats and very few (if any) nonrevs, it's worth considering. The upside of doing this is that if they still have a seat in First by the time it's your turn in line, there are no service charges for it. I've done that twice. Once on an A320 ORD-MSP with about 50 people booked and 2 other nonrevs, another on a CRJ-700 DEN-ASE with 4 other people (all misconnected the night before). Both times I was the only passenger in F.