24. In determining the amount of his fees, an appraiser shall consider the following factors in particular: (1) the knowledge or skill required to perform the professional services;
(2) the degree of responsibility assumed;
(3) the degree of difficulty and the importance of the professional services;
(4) his experience;
(5) the performance of professional services that are unusual or that require exceptional speed or competence;
(6) the tariff suggested by the Order for the professional services rendered;
(7) the time required to perform the professional services.
No appraiser shall determine his fees, in whole or in part, as a percentage of contested taxes saved or a percentage of an expropriation indemnity surplus.