The Olympics will put an unbelievable amount of strain on a person's mind. Over the years, a few methods have been found to slightly reduce the impact that that pressure can have. Most archers prefer to avoid being able to fully control when they'll actually shoot. They use a technique referred to as random/surprise release.
This method massively reduces the risk that they'll flinch at the last moment. Instead, their shot will be fired at a relatively random moment so their body won't be able to anticipate it. There are many methods to achieve this. This is obviously taking the easy way out, but that's what winning often requires.