No I disagree, You can technically make it as short as needed, although if you are using them on a patch panel or switch you would like to leave all of them long enough to reach corner to corner diagonally in case of issues with other cables. There is not a length that is too short unless it wont reach what you need it to ; )
Here are some more details if you need more information.
I’m fairly certain that 18 inches is supposed to be the minimum and you should not have any cat5e in excess of 250-300 feet.
Hope this helps!
There are certain instances where the 15m minimum is required. But if you are not using consolidation points that is not a requirement for CAT5e. If you are using consolidation points, you can leave a service loop (slack) in the cable.
— Carrie Higbie, SearchNetworking.com infrastructure and project management expert