Upon adoption of a reasonably final plan of improvement for the beach and shore preservation program for the entire county, the board of county commissioners shall conduct, through the use of personnel competent and qualified in this field, an economic analysis of the proposed program, determining the nature and extent of benefits expected to accrue from the program and allocating these benefits to their proper recipients by categories or zones of comparable benefits, and place in the same zone areas of equal benefit, or follow such other method as may be deemed suitable for the purposes of this section. From time to time, the board of county commissioners shall conduct in the same or similar manner a new analysis to better determine and allocate actual or expected benefits.