Any reason not to refactor this macro impl to only insert x once instead of twice? https://github.com/clojure/spec.alpha/blob/master/src/main/clojure/clojure/spec/alpha.clj#L1939

seems like it would make the compiled code smaller with no downside I can see

happy to make a ticket&patch

(I assume you could also demonstrate exponential macroexpansion blowup by nesting s/assert calls)