Wankery is usually a reflection by those making the comment that the instrumental moments during a progressive tune are not so good or not working within the confines of that song. That again is an opinion which could and probably will be contested but generally that's how I take the comment 'too much wank' within a track.

I personally take this as not good prog.

IMO good prog is displaying good song structure, making something that wouldn't normally fit actually fit within a genre etc... it's all open for discussion but to my ears I do not class 'circus sounds' thrown into instrumental moments during Systematic Chaos as good progressive music. That to me is completely and utter toss!

For some it may work for others it doesn't work, IMO.