The original home of the Shadow Guardian Stable was a single building erected as a group effort by the Guardians themselves, and then augmented and completed with Jade's powers.  When the acreage was purchased with the eventual construction of the Manor in mind, consideration was also given as to what would be needed for SGS.  The end result is what you see here.  Perhaps it did seem excessive at first, when then stable manager Tristan Slaytir laid it out and oversaw its construction, but already the stalls are full and space is at a premium.  In fact the continued need for space led to the development of the Tanglewood Equestrian Center.