mango,this topic was discussed deeply a few days ago.and imo,you should have never used the fence for a guide or a training tool to begin with.
Some folks do not have the ability to feel or anticpate and correct before a complication arises.
My horses side pass beautifully when the correct buttons are pushed. If I am teaching a person how to execute a side pass and my horse is not doing it correctly, the wall is a good teaching assistant to help that person understand.
If I have a horse that insists on moving forward or back when I am asking for 'over', it takes one less distraction out of the equation for the poor horse.