No, they don't: gymnastics has an open ended CoP even in every apparatus, included vault. Of course it's only one trick, but you can decide to make it as difficult as you can perform; i.e.: you can extend the D component of the score as far as your skills go. ---- Your reasoning applies to the current figure skating CoP too: let's say that every planned element will be completed earning the highest possible GOE, bam, you have your top TES value, which you can only deduct from. And yet still the figure skating CoP is open ended, because no one is gonna stop you if you want to jump a quadruple insted of a planned triple, if you can - (and granted that you meet requirements, as in gymnastics). ---- Gymnastics vault would be like peforming a single jump: once you're going for one specific element the TES value is set (D score in gymnastics), and the final score is only a matter of GOE (E score in gymnastics). -- We can skip the under-rotation thing, as it would be like piking a vault that was supposed to be straight, it only brings the actual TES/D score down -- But: you can always go for the jump you want, hence, the TES score does not have a fixed top value.