The McDuff One-Hit Wonder Rule ©

A One-Hit Wonder is an artist whose most successful song is the only song that they release that enters the Top 20 of a particular Chart.

Rationale:

Identifying a One-Hit Wonder should be done according to a certain Chart (USA/UK/Australia etc.) Ideally the claimant should identify the Chart being referenced, either directly or by implication. The term One-Hit Wonder should not be used if a Chart is not being referenced.
Applying the term One-Hit Wonder implies at least a modicum of success so the McDuff rule focuses only on the Top 20 of any Chart. This allows for varying Chart sizes and takes into account artists whose most successful song is a smash hit and this success tends to ‘spill-over’ onto the subsequent release which is often much less successful.
In a broader sense the McDuff rule classifies a Top 20 song as a ‘Hit’ and a non-Top 20 song to have merely ‘Charted’.

A Note from the creators of the McDuff rule

Being baby-boomers and very fond of popular music, we found that we were constantly arguing over who was and who wasn’t a One-Hit Wonder. Occasionally, we were offended at the liberal application of the term to artists that we loved and had followed for many years and wondered what criteria may have been used in order to come to such a conclusion?
The term One-Hit wonder is here to stay so the McDuff rule is our attempt to bring order to its application. We hope that with its general acceptance that popular music fans everywhere will be assured that the use of the term One-Hit Wonder is both appropriate and justifiable.

Andy McCarthy and Danny Duffy – Adelaide Australia