If 14 shootings killed 156 people then at least one killed 11, I think we would have heard about it.
More than that even. 156/14 ~ 11.1, so if all 14 of these shootings had 11 people killed, the number would add up to 155. Obviously it’s unlikely that all of these would have exactly 11 people die. Most would have a much lower number than that, so some of these would have to be like 15+ people killed. Obviously there’s something wrong with these numbers
The real average deaths per mass shooting was 0.65
https://thehill.com/blogs/blog-briefing-room/3506536-9-killed-in-14-mass-shootings-over-holiday-weekend-watchdog/