Great post from LastStandards - and yes, there IS an issue here. A big one..... There is no excuse for any controller not having a grasp of the risks involved with wake turbulence, even if the exact scenario is not quite as described in MATS1.
While I would acknowledge that if able, then the training scenario to which the instructor is working should be respected and granted. If for no other reason than simple politeness. If able... But training flights are a lesser flight priority than Normal Flights. That is a fact and should be borne in mind by both parties. At my last station, this was not the case and scheduled traffic would be held on the rwy - sometimes for up to 5 minutes - waiting for a release from radar while a trainer went around not below 700', asymetric, standard missed etc. Really got me irritated as not expeditious. No attempt being made to come up with a solution to limit the delay. (Plenty of options!)
I also recall at a beloved former station, when as a relatively newly validated tower controller it really started to kick off. I forget the exact details, apart from the fact that in the middle of all this chaos going on on the ground with departures etc. there was a DA42 bimbling down the approach. EXAM callsign, IFR check-out. Whatever and why ever, he was getting closer and closer to his go around. In the end - when I finally got around to it! - he got the "Cleared to land, land only" call. This was a piece of phraseology we used, maybe not frequently, but when wake turbulence was obviously an issue. In this case it clearly was. The examiner came back - and no doubt trying to help me out as it was obvious I was really busy - said he was happy to accept and early left, visual, and to apply his own wake turbulence separation. Unfortunately, WT is NOT at the discretion of ATC (or instructors...) so he got a negative. The student performed a perfect landing, taxied round and departed again in total safety.
The point of my post is thus that while we should all try and accommodate all requests it is not always possible. Training flights have to accept this - and their lower priority - and I'd suggest that there is excellent training value to be gained from being prepared as much as possible for ALL eventualities. Go-arounds when the mind-set is to land, landings when the mind-set is for the go-around. (What, prey, happens when on applying GA power, splutter, splutter - engine dies? !!) And all variations in between.
And before anyone chips in and reminds me, I am well aware that EXAM callsigns are the same priority as normal flights! But my example is offered to illustrate real life.
I phoned the flight school later and spoke to the examiner. The student passed with flying colours, he being particulary impressed with how he handled something unforeseen being thrown at him!!!!!!!!