And one thing that bothered me and might have already been addressed...but isn't it a bit hypocritical to go on ranting about the instructors teaching to the standards and following the rules when you yourself thumb your nose at a simple one like not using Nitrox w/out the proper training/certifications??
Breathing (not mixing, USING!) Nitrox mixes under 40% require exactly two computations to be understood to be done safely.
1. How to compute the MOD of a mix, given a desired exposure (PO2 of 1.4 or, if you prefer, 1.3 to be more conservative) so you know the MAXIMUM depth you may dive to on that mix. If you have a hard floor above that depth, you can safely ignore this issue, but you do need to know how to compute it.
2. How to compute the END, so you can use an air table to plan your dives.
These are two basic algebraic computations. The rest is window dressing; yes, you need to know how to mix Nitrox if you're going to do it, and you need to know what protocol is for oxygen service if you intend to actually take care of that side of it, but if someone hands you a tank of mixed Nitrox and an analyzer, and you verify a mix of 32% O2, then the two above calculations are the
only additions to your basic OW training that you must be able to make in order to dive that mix safely.
There is nothing complicated about this. In fact, many agencies don't even demand that you perform a single dive for this.
Fundamentally, air IS Nitrox. To omit two computations from an OW class is nothing more than an attempt to grab more money, and IMHO its foolish to feed that troll.
BTW, what a difference a weekend makes. Funny how diving with the objective of working on this issue turns something hard into something where much progress is made. Its clear that its not a matter of it being hard - you simply have to introduce the concepts and actually spend some time on them!