According to IMDb rules, any movie with a runtime of 44 minutes or less is a short film. However, the only way to have a title identified as a short film is by adding the short genre in the genre film, otherwise, the title will appear as a feature despite its runtime.
Over the last months I have added the short genre to hundred of titles that were missing it and that are reported to be 44 minutes or less, even dozens of 1 minute long titles appear as feature films, because they are missing the short genre. While I have managed to reduce this list a lot, whenever I leave the work for a few days, the list grows again with new titles not correctly categorized. the current titles in this situaiton are here: http://www.imdb.com/search/title?runtime=1,44&title_type=feature
My suggestion is to improve the updating section, by adding a lock that avoids to add a new title with a runtime of 44 minutes or less without the short genre (unless it is tv of course)
This happens for example in various genres, where you get an useful reminder. For example the film-noir asks you ot to add title outside certain year range, the documentary genre reminds you to only use it in full documentaries and the adult genre reminds you to add some mandatory keywords.
In this same way, the updating for should tell you: you are adding a runtime of less than 44 minutes, if this is true then you need to add the short genre to this title ̈ or something like