Should you run a hepa filter all the time?

Since air pollution is a widespread and ongoing problem, it's best to leave the air purifier on all day. Keeping the unit running all the time is not inconvenient and, if the filters are changed in time, can help reduce contaminants in the home. Some purifier companies recommend running the air purifier all day long. But is that really necessary? If so, isn't running the purifier all the time a big waste of filters and energy?.