Some purely personal observations ..
All too simplistic and typical of some flying schools.
That may be true however simple rules form the basis of SOP - when the action happens and the adrenaline starts pumping is not the time to be going back to developing strategy. A rule-based protocol may well not be the best strategy but it might offer a reasonably considered option in most situations of interest
In any case, Blue line speed is nothing more than best rate of climb on single engine ...
OEI, the speed range for climb capability is narrow and narrows rapidly as weight and DH increase .. rapidly becoming non-existent. Best climb speed sounds like a pretty important number to me.
Another speed quoted in some POH is best angle of climb speed to clear obstacles which still gives you a positive rate of climb although not necessarily as good as Blue Line.
I probably wouldn't like to put my trust in that philosophy ...
There is no published "Decision" speed on light twins.
Depends on what the OEM chooses to include in the POH.
Same as an earlier post regarding "Decision height" for asymmetric go-around. None is published in the manufacturer's AFM/POH ..
But may be. This aspect of OEI operation is looked at with some attention for military acceptance - unfortunately not routinely in civil practice.
Blue line speed = decision speed so there is no 'in between zone.'
Unless the overrun is a cliff drop off or some other dreadful thing ... sounds like a useful rule-based strategy for light twins. Given the rapidity with which one can lose those few knots .. I preferred to target a speed a little in excess of blue line ..