The Standard is not to Superman, but to disconnect 1 tank at the rear connection. The logic is that you will want to be fluent at this so you can disconnect 1 tank as you approach the boat so you can hand it up before climbing the ladder.
Being able to hand up your tank for boat diving makes a lot of sense but doesnt this skill also require the diver to be able to unclip+remove the long hose and disconnect any inflation hoses (whether it be a drysuit or a BCD, depending on which side the long hose is on) under water? Since I would argue that its easier for beginners to unclip the tank and detach all hoses while holding on to a ladder or doing this at the surface, Im wondering why this particular skill is considered to be a mandatory skill while diver and tank trim and buoyancy control are merely optional skills.
I'd list the following reasons;
1) Developing equipment familiarity and ingrained muscle memory; especially with the cylinder bolt-snaps. Many students initially struggle with the operation to attach/detach cylinders, even at the surface. This is more practice with the kit, developing 'feel' for manipulating the snaps and the cylinders.
2) It provides a simple option for the sidemount diver to neaten/stow their hoses on the cylinders.
3) It helps develop awareness of cylinder buoyancy characteristics.
4) It is an initial orientation into the full capabilities of the sidemount system. Consider this something of 'beginning with the end in mind''. It highlights equipment performance capacity. It doesn't "train" for restrictions.
5) It provides some option for recreational overhead divers (esp. wreck) to utilize the equipment to escape from an otherwise dangerous situation. I teach my recreational wreck-sidemount students to never pass restrictions, but to remain aware of exit options that sidemount would permit in an emergency.
Yes, I agree with most of these points but I think these almost superfluous when compared to basic buoyancy and diver/tank trim skills. The equipment performance is lessened with poor technique and, with only 3 dives to cover basic skills, Im not sure how necessary unclipping tanks at depth + swimming for 60 feet helps the divers to achieve good technique.
As for #3, I would argue that teaching tank trim skills versus swimming with 1 tank out in front gives the student more awareness of cylinder buoyancy characteristics.
As for #4, I've had an experience where I performed a bubble check at 30' and then realized that my inflator hose was leaking after unclipping and swimming with a tank in the front. Luckily my teammate pointed it out right before it got worse, and I was very comfortable with doing valve drills at that point, so I closed the tank and called the dive. My follow-up question to this point is then why wouldn't valve drills be included in the syllabus if 'beginning with the end in mind'?
As for #2, I recently learned that you can easily neaten/stow hoses by also unbungeeing and holding the 1
st stage which I found to be much easier than swinging the tank out in front with AL80s. (I havent tried this with steel tanks though).
I am not an instructor and have only been diving SM over the past year (however, I logged multiple dives a week in varying conditions over this time in SM) so I bring these points up from the perspective of a student. I admit that in the beginning I unclipped my tanks since I saw others doing it and it looked cool.

However, when I took my full cave class last week, my instructor taught me that unclipping tanks for restrictions is actually beyond the scope of my training so now I'm going to focus much more on perfecting the fundamentals of SM.