If the immunity period is unknown/short then isn't there some logic in trying to build heard immunity amongst the entire lower risk group before the immunity wo

If the immunity period is unknown/short then isn't there some logic in trying to build heard immunity amongst the entire lower risk group before the immunity would be lost. If we shut everything down for a bit, then start returning to normal life, that would stretch out the timeline for everyone being exposed and risk creating a cycle where people get it over and over again.