Thats an interesting question. I like to go about a year and them they get put back on the shelf unless there is a theme or something like that; but I am also guilty of bringing one to every contest hoping that it gets noticed but doesn't but I keep hoping. Over here in my neck of the woods some guys keep bringing the same car and keep winning the class year after year with the same car. These are judged contest to boot, you would think that the people judging would notice this right? They don't and these guys just keep doing it. Maybe this is more of a rant then a answer but it just grinds at me that some guys get all the awards with the same car year after year and don't bring anything new to the tables. Oh well this is suppose to be fun and not about awards. If I want one bad enough I can spend the 5 or 10 dollars and make up my own. Sorry if this offends anyone just my thoughts on how long a model should be competed