Sure, but a toy problem that's substitutable for many other functions. In this case you could substitute the XOR function for any other merge function. As far

Sure, but a toy problem that's substitutable for many other functions. In this case you could substitute the XOR function for any other merge function. As far as the variable depth is concerned, utilisation is an issue that introduces additional complexity, but otherwise I don't see the problem. (No one's expecting fixed compute time for differently sized data elements.) You can get around that one by building a log(n) threaded pipeline for your log(n) depth network (something like this: https://imgur.com/a/xL4rhFu https://imgur.com/a/xL4rhFu).