Practiced too often, this technique developed to build strength and break plateaus becomes ordinary and loses impact physically and psychologically. You stand the chance of becoming dependent upon a partner, your training may become rigid, and there's the risk of tendon and joint overload, muscle tear or overtraining. When performing serious assistance training, be prepared for some extended repair and recuperation time. Training partners are great while they last. Some last forever, some won't go away.
Problems arise in setting partnerships in motion.
There needs to be personal connection, physical compatibility, goal alignment, matching zeal and timing. When one partner is lost or late, precious time marches on. Tough training is a psyche and misplaced time frustrates that valuable cerebral spark, leaving you dull and sluggish. I don't want to hear about the horse on the freeway or the baby you delivered in the elevator. I'm loosing my pump here.