A convention is an accepted best practice to achieve a goal. Standards dictates the only acceptable way to achieve a goal.
In my opinion, if you wish people to be productive and focused you have to give them ownership of something. You should specify the level of quality you wish from the output, but don't dictate how something should be achieved. As soon as you specify the only acceptable method for achieving a goal, there is no room for creativity and ingenuity. These are the two resources that a company has to make use of to succeed, and no amount of money will convince someone to bring then to work. If there are recognised best practices to achieve a goal, then these should be shared. They should always remain conventions not standards.