My outlet to field is without d box or manifold. What is with the "left, right, left, etc. dispersing tiles?
A leach field with a distribution box will allow a larger flow rate compared with a single back and forth pipe with no d-box. Peformance of a single back and forth pipe is further impaired if the field is sloped overall from one end to the other because there are uphills in the pipe path. This could pose a problem when large flows occur such as from using several plumbing fixtures and/or the washing machine at the same time.
The average homeowner who lost his house in the Oklahoma tornadoes should move for good and not rebuild. Too much complexity watchdogging the contractor. Too much a chance to be defrauded.