The net amount to be asessed upon lands within an assessment district may be apportioned by any formula or method which fairly distributes the net amount among all assessable lots or parcels in proportion to the estimated benefits to be received by each such lot or parcel from the improvements.

The determination of whether or not a lot or parcel will benefit from the improvements shall be made pursuant to the Improvement Act of 1911 (Division 7 (commencing with Section 5000)).