Depends, my employer (hp) bought a buttload of them and handed them out when we had local spikes. At one point I was doing them every other day, now down to onc

Depends, my employer (hp) bought a buttload of them and handed them out when we had local spikes. At one point I was doing them every other day, now down to once a week. They cost around $20 for a 2 pack here.