Are there any universal rules for individual prizing?
Not really. At the Olympiads three medals are awarded for best individual percentage results obtained at each board. But in the past it was not always the case. Sometimes only board winners received prizes (or medals). Sometimes (1939 Ol) only the championship final results were taken into account. Sometimes (1958 Ol) only one individual prize was awarded (best result at board #1). For other events the rules are not strict and depend mainly on event regulations. OlimpBase notes only board winners for minor events unless other regulations were explicitly set.
