If you use a progressive with auto-indexing - it’s very hard to screw this up and end up with a double charge. But some people are very clever in make anything unsafe..single stage is no problem, it’s progresives where the danger is and it could be no charge or double charge. if i load pistol on a progressive i look at the charge in every case. but it only takes missing one to cause problems. the charge indicators are the only way to go in my view.