One intermediate control is the correct number for a 200. Two at a pinch. Three if you must. More than that is superfluous*.
Note that the org's handbook is out of date on this matter: at the last AGM I spoke for the motion to remove the need for organisers to position controls such as to get riders to dismount and top up, and this motion was passed (actually irrespective of whether I spoke, as online voting meant it already had the necessary majority
). Therefore riders are responsible for planning and making their own refreshment stops (if any), and organisers can place controls where needed for minimum distance; if the two coincide then that's nice, but
not necessary.
My two 200s have one and two controls each. As it happens, both have ample opportunity to stop mid-stage for a cuppa, if needed/wanted by individual riders (and there are plenty who ride straight thru without stopping, myself included).
Just to add — this is an Audax UK point of view, other countries may have different requirements.
* IMO.