Doctrinal classes should be taught by those who are educated in Doctrine. Those educated in Doctrine would be the Pastors, correct? Those who are "called" by the church?
We all have a teaching role, of course. But in a public teaching of the church, this should be done by the Pastor.

It is not that we are trying to burden the Pastors, rather we are trying to appropriately shepherd the flock.

In Reformed Theology there is the "teaching elder", correct?

Grace is not common.