Employees should be evaluated regularly. The software was designed for use in a periodic system, such as monthly, bimonthly, or quarterly.
To compensate for a "bad month" or two, more evaluations are favored over fewer evaluations. Monthly evaluations are suggested, with bimonthly next in line. While the software can be used for quarterly evaluations, this scheme only produces four evaluation periods - not enough to include all of the good things that the employee does.
More frequent evaluations are better. Once the supervisor/evaluator gets used to the software, completing an evaluation will take about ten minutes.