In all my yrs rarely, like I can count on one hand, thru-hikers reserving shelter space for another thru hiker ON ANY TRAIL WITH SHELTERS. MOST OFTEN PEOPLE DOING THAT ARE SELF ASSUMING ENTITLED SPECIAL OR PRIVLEGED GROUPS LIKE SCOUT and FEMALE ONLY GROUPS and SECTION, WEEKEND, or WEEK LONG HIKERS THAT ARE COUPLES. - HIKERS.
I'ver NEVER seen a THRU-HIKER in a packed shelter erect their shelter in a lean to taking up more than a 1 p space. I certainly have seen self entitled assuming section hikers do that several times.
AND, if I really wanted to take this thread further sideways revealing how inconsiderate and imposing - entitled - some hikers can be I immediately can name two categories that IMHO outweigh the imposition of the AT thru-hiker used category.