This would depend first on the material of the hooks. Most stainless fishhooks are certainly not implant grade stainless, and therefore should be removed after suspending. There are some custom made hooks on the market made from implant grade materials and that are specifically designed for suspension. These hooks could, at least from a materials point of view, be left in for very extended times.Once the hooks are put in and the person is prepped for suspension, they have roughly an hour to chill with the hooks in. However, the longer they wait, the less endorphins will be flowing, and, additionally, drying fluids around the piercings will make them more painful - it is best to suspend as soon as possible after the piercings are done.
Once down after a suspension it is best to remove the hooks and burp out the air as soon as possible.