I don't know of any systematic studies, but the balance of available evidence is that warrant approval rates are very high: https://www.washingtonpost.com/news

I don't know of any systematic studies, but the balance of available evidence is that warrant approval rates are very high: https://www.washingtonpost.com/news/the-watch/wp/2017/08/10/no-knock-raids-like-the-one-against-paul-manafort-are-more-common-than-you-think/ https://www.washingtonpost.com/news/the-watch/wp/2017/08/10/...