It is never 'standard' to add a modifier. The modifier should be added if the provider or the coder believes it is required to correctly indicate the services that were performed. If you are billing and you are aware that the code is not covered without the modifier it would be a good idea to bring it to the attention of the provider or coder. They may not have realized they need to consider the use of the modifier, but they need to decide if it is appropriate for the services that were provided.
Michele