Cindy/Murph/Severin
We did Severin yesterday in class as a team WOD.
It seemed to me like 1.5 Murphs, but strict and without the squats.
Also Cindy has the same movements as Murph, without the running.
Is there a reason why there are three so similar workouts?
I'm not an expert by any means, so anyone can correct me. But I don't think there's a particular reason. Taking into account those movements are fairly basic (pull-ups, push-ups and air-squats), then they are simply different versions of the same WOD, named differently just because. Maybe the ones who created it wanted differently on purpose, maybe they didn't know each other and came with them at the same time. I don't think there's a particular international entity that governs these things.
Yeah, those movements being the standard movement might be a good reason. Still the rep distribution etc is also really similar.
Regarding reps, I guess it's a thing of calibration. Usually, you do less pull-ups than push-ups, because the muscles are smaller and get tired more easily. The same go for air squats, where the quads are massive in comparison to your pecs and delts. Unless you are skipping leg day every day and you're shaped like an inverted triangle, then it can be whatever.
It reminds me to this chart of cardio conversions. There might be something similar for own weight exercises depending on the muscle group.