The element of the weight to be accorded the character of the veteran's service is but one factor entering into the considerations of the rating boards in arriving at determinations of the evaluation of disability. Every element in any way affecting the probative value to be assigned to the evidence in each individual claim must be thoroughly and conscientiously studied by each member of the rating board in the light of the established policies of the Department of Veterans Affairs to the end that decisions will be equitable and just as contemplated by the requirements of the law.