There are many factors that causes haze / cloudiness. Gelatine does work and clears beers faster than what they may without gelatine on some aspects of haze.
Some hazes form at colder temperatures, as mentioned. These aren't cleared by gelatine. There are ways to clear and reduce these too, and there are lots of articles on the forum here if you search. But Gelatine is a simple and effective way to clear many beers. Great place to start.
Other products that can be used, but must be used in the right way and in the right circumstances will clear most other hazes especially when combined with filtering. Although filtering alone is no guarantee to a bright beer either depending on how the beer is treated and at what temperature. Polyclar, Isinglass, Brewbrite.
To answer your poll. Yes Gelatine, it works on some aspects of haze. No hesitation to use it.
On the other hand I like cloudy beers, but I do understand the judging aspect for a beer that must be bright. Yeast choice can play a big part here too, look for yeasts that suit the style with a high flocculation. Some drop remarkably clear all by themselves.
Cheers Steve