As someone who works in HR, I know there is genuine work related stress and there are those who perform poorly at work who take months off.
Some people go off with stress the minute they become subject of a disciplinary investigation or the capability procedure.
They go off for months not wanting to face the issue.
I've known employees threaten to go off sick of they are put on capability.
I also know that some managers are useless and actually cause the stress. They have poor people management skills and dont know how to talk to people respectfully.
I've had managers and employees send me emails asking for support with either the employee and the manager. When I see the email trail... I just SMH. I've often said to managers that their choice of words caused the matter to escalate.
What I mean in plain english is they were bang out of order. I just have to be diplomatic in the interests of collaborative working.
A large number of those who go off with work related stress are known as difficult employees. Pains in the rear to manage... and they are totally lacking in self awareness.
Nobody ever believes they are difficult... but everyone else experiences them that way.
I'll never forget a colleague saying that a workman at her house said she was the most difficult customer he'd ever had.. she actually said to us...
"Can you believe what he said?"
Of course we could believe it...she was a bloody nightmare...but with no insight whatsoever.