First, not that many executions overall.
Number of Executions by State and Region Since 1976 | Death Penalty Information Center
Less than 1,500 in the last 40 years. If you pay attention to the media, it sounds like dozens are happening every week. Keep in mind all the horrible folks doing really horrible things. Take the flip side: one person is claimed "innocent" and the entire US justice system is accused of being so, so horrible. Does it happen? Absolutely ... how often in reality? Get real ... Not much thought about the victims and how their family's , friends', and loved ones lives are ruined forever.
It's a final decision so to speak and a decision which needs to be made. Personally, these horrible folks should suffer years and years in really horrible conditions, as brutal as possible. Unfortunately, we cannot treat prisoners this way.