on left bends in order to avoid overtaking drivers you need to actually make it tighter. Which I always do. Contrary to the concept to stay close to the white line to gain "visibility". I mean you can go to the white line before the bend and take a glance, but than stay out of the white line. Better safe than sorry
The IAM rule is "Safety, Stability, View" in that order, ie getting a good view through the corner is only done *after* making sure you're in a safe position (or one that you can make safe) and you're not going to get destabilised by road crud, diesel, cats eyes etc which could put you in a dangerous position.
I have not seen any IAM videos but did see quite a few videos posted by a police instructor using the ROSPA system and at times found the road positioning put riders into a potentially dangerous situation. He was posting on the MCN website and several of us picked this up, he had someone under instruction and on a left hand blind bend he had them sit on, or very close to the white line giving them the clearest line of site through the corner, fine, we could see that this made sense, except this allows very little room for manoeuvre if someone was to come in the opposite direction and slightly cut the corner. He tried to argue that this was not an issue but in the video you saw a car in the distance on another corner clearly over the line in what would have been the riders space had he been there.
I would also argue that providing your speed isn't excessive then being on a tighter line allows you extra space to adjust your road position if the corner was to tighten up dramatically. You could run wider and apex later without the risk of running over the white line, something your going to struggle with if your already on it. Now I understand how you use the vanishing point and the fact that you adjust your speed according to the distance you can see, but I still would say that if you were caught out by the radius of the turn you would be in greater danger than someone on a tighter line.
I believe any training is worthwhile but for me I wouldn't want the system to be so ridged it didn't allow riders to think for themselves in certain situations