I think that chart of SS vs CHR vs DET is more about theoretical attacks on a dummy for an inordinate amount of time. In real fights you rarely have full upkeep, regardless of skill, so I look at it much more about practical application rather than a theoretical situation where you're standing still punching one enemy over and over.

I'm not a fan of SS. In actual FFXIV fights, it's not constant where you can do the amount of casts needed to reach breakpoints where you do an extra attack. In almost every end-game fight worth its salt, you gotta occasionally-to-frequently interrupt your cast because of AoE dodging, phase shifts, mechanics that require moving, etc. Every time Ifrit, Garuda, or Titan jumps up or teleports for an AoE, or you gotta dodge a things, you better have reached a break-point where you got an extra attack already or it was likely not a DPS boost to build for SS. The biggest argument for SS is it can let you have reached a break-point before every time you have to stop attacking, which is a fair point but hard to put a value on because it's so fight dependent and luck dependent in many ways.

I'm a much bigger fan of DET, which is more consistent. DET works every single attack and is a guaranteed benefit regardless of if you're not dodging or if you have to move once every 10 - 20 seconds like the EM primals. CHR is very RNG impacted, but it's an average damage increase regardless of the situation, and the most useful stats for adds and mechanics where more DET probably won't let you kill an enemy in less GCDs.