JMeter - Why once only controller runs more than once

Question

I added two request one for login to store the session id and another request to check the load test which requires session id.

I made login request as once only, by ad

Answer 1

Only once controller works the way BlackGaff explained it.

What you are trying to do seems wrong as it would mean you authenticate your 100 users with same login/password.

But if you still want to do it, you can use setupThread with one user, it is usually useful for some init task on test but in no mean it answers your requirement which seems wrong to me.