Ive worked at schools which have no standard policy implemented by the CFI and it just confuses the student, as this is the sort of low standard school that always swaps the stude to different instructors who then go about saying-"no dont do it that way do it this way". Its a bit like trying to act out a play with everyone directing themselves, it cannot work.
I cannot quite agree with the way you phrased that, quote
Icing can occur at any phase,
.
Thats an ambiguous statement that needs qualifying.