According to my modest opinion, human strength is almost unlimited: I have seen so many people enduring hard things and still hanging that I came to this conclusion. Many things are in fact not physical but purely mental (or spiritual) like they say in some documentaries in which they show recruitment for special forces.
What does a "spiritual father" know about you after a first discussion, then a second discussion, then a third etc? Seeing how confessions are conducted in most cases, 3 minutes before liturgy and with speed because there is a queue behind (which is contradictory with the way confession should be made), I doubt the confessor remembers you (particularly in big places) or even knows you, unless you arrange some long meeting with him. Add to this that in many cases, in Russian parishes, the persons confess to any priest available (so the priest will change), there is a serious lack of knowledge between one another allowing to give personalized advice.. Add to this, that spiritual fatherhood is a serious choice by the two person : you cannot ask a priest to be your regular confessor or spiritual father without knowing him (see advice in Saint Nikodemos about choosing a spiritual father -i.e confessor- of experience, like a good doctor). The notion of spiritual fatherhood (or motherhood) is really worth discussing (I will open another discussion) because everybody likes using the word but the scope is very fluctuating, along with the expectations of the different people and the reality is what it is.
Many books written by Saints are in fact recommandations of spiritual fathers (true saints in this case) for people in general or for particular cases, that is why I give them much credit for guidance : they were written by people with spiritual enlightment for sure, so that makes them good guides, according to me the best. So, I would find quite reassuring that a confessor makes reference to writings from saints and tells it. I remember the first one I had in world orthodoxy used for penances the canons of Saint John the Faster (I think he might have been one of the few ones in Paris giving penances by the way). It indicates that what he does is a heritage from an old tradition. But the one giving advice coming without references would be quite worrying for me.
In my case, it worked very fine for me reading Saint Nikodemos, that, actually, acted (acts) through his books (Manual of Confession and Christian morality in particular) as a spiritual father. But, it is my case.