Thanks to JST online guild I have been weaving since 2018. I have a 36" Schacht floor loom at home. When I first learned to weave, I used an iron warp rod to attach to the wooden apron rod, as Jane taught us. I never successfully hooked those 2 together without messing up my warp cross (back to front). Lately, when I started teaching students at a center that has only old looms the students had the same challenge.. In addition, the rods are bowed. I noticed while watching YouTube videos from EugeneTextiles, that they do not use an iron warp. She just slides the warp onto the wooden apron rod. Consequently, I have stopped using the warp rod at home and am doing the same. Never bends.
However, I don't want to teach my students incorrect techniques. Is there a purposeful and important reason to include the warp rod to the attachment to the apron rod at the back beam?
Thank you.

You've been following the School of Weaving long enough to know that there is likely no question in Jane's world that is answered "you must" or the " rule is" ;-) ..... Different looms work in different ways and you have to discover what works best for the loom you are working on. I can't imagine the amount of tug that went on those old looms that made the iron rod bend that way. The rod is usually used so that you can lash your warp from the rod and secure it right across the wooden apron rod. My guess is that the weavers using those looms didn't go the extra step by lashing the warp to the apron rod or that rod would never have been able to bend that way. It also shows how previous warps may have been uneven because of the iron rod slowly bending out of shape. You must find a way that works for you and your loom.