When I was working as dive master / instructor I usually did use at least three second stages and two first stages (on a 15-liters single).
At least one of them (possibly two, when using 4) was mounted "from the left", so wrong for me, but very practical to be given to a client/student when in need of air.
Now I am just a normal rec diver, so I use a setup with three second stages and two firsts stages only in very special conditions (caves, etc.).
In normal diving i use a standard single first stage with two IDENTICAL second stages, both coming from right, and both with a 100cm hose. So both can be easily donated, albeit not as easily as if one was mounted to the left side.
During the dive I usually alternate the two regs, so I know that both are always working well.
In case of an OOA emergency I will give the one which is more practical: at that point there is no real difference, as the regs are identical (109 converted to 156), both work for sure, and in such a case COVID-19 is the last of my concerns...
At least one of them (possibly two, when using 4) was mounted "from the left", so wrong for me, but very practical to be given to a client/student when in need of air.
Now I am just a normal rec diver, so I use a setup with three second stages and two firsts stages only in very special conditions (caves, etc.).
In normal diving i use a standard single first stage with two IDENTICAL second stages, both coming from right, and both with a 100cm hose. So both can be easily donated, albeit not as easily as if one was mounted to the left side.
During the dive I usually alternate the two regs, so I know that both are always working well.
In case of an OOA emergency I will give the one which is more practical: at that point there is no real difference, as the regs are identical (109 converted to 156), both work for sure, and in such a case COVID-19 is the last of my concerns...