Zevachim 19: On Belts, Interpositions, Sanctification, and OCD

We stay on the topic of priestly clothing.  The beginning of our daf focuses on the belt.  Where should it sit?  What if the belt was too high or too low?  The rabbis consider the permission given for a priest to wear a reed around his finger if it has been cut before a Torah service.  The rabbis consider whether or not this or other items might be standing in the way; interposing.  

A conversation emerges regarding other potential interpositions: would a louse between a priest and his clothing count as an interposition?  If it is alive, it is moving, and thus might it be permitted?  What about a gust of wind that might lift the vest which has been described as being on the priest's body?  Of course, dirt interposes.  But what about the "dust of dirt", dust that cannot be seen?  Or the area under the armpit which is always left uncovered?  Or one's hair, which might slip out and interpose between the vestments and the body of the priest?  What if a priest touches his own chest?  The rabbis spend more significant time discussing tefillin: an interposition between the priest's clothing and his body?

The Gemara details a debate about hand and foot washing - sanctification - before the morning and evening services.  Would imprecise hand or foot washing invalidate a priest's service?  What type of washing is necessary?  At which times?  How many priests could be accommodated at the basin at one time for kosher sanctification?  How much water was held in the basin?  The rabbis determine that ministration of sanctification was done while standing, as stated in the proof text: Deuteronomy (18:5), "To stand to minister".

Toward the end of our daf, the rabbis further consider when a priest should sanctify his hands and feet.  Is once each day enough?  What if it is done only in the morning?  Or only in the evening?  What if certain types of work were done in the hours that followed sanctification?  

Again, I recognize commonalities between Talmudic debate and symptoms of obsessive compulsive disorder.  The rabbis are searching; yearning for a definite answer.  But how is there ever a lasting ritual purity?  Once the moment of sanctification has passed, how long can we consider ourselves ready for prayer?