Offset holders are designed to allow one to reach into or over something on the part. They are designed to withstand most welding forces with very little flexing. Offset holders should be used in machines and set ups to minimize any other bending forces.
A long rocker arm welder would not be a good set up for an offset holder to minimize flexing motion. Using an offset electrode in the offset holder also compounds the situation. Not to say that these set ups are not being used every day. Excessive flexing means that the face of the electrode is rocking on the part. So the ¼” flat face of the #5 RWMA electrodes has rocked back and is now resting on an edge. Too much power will be applied for this reduced surface area and expulsion will occur. A new face will begin to form and eventually a steady state condition will be reached. Then you dress the electrode and start all over.
Offset holders perform a needed function but must be used properly to maintain good welding practice and quality.