By the time I did my AOW, I probably had as much exposure (in terms of variety of environments...deep, night, drift, boat, nitrox (certified), limited vis, cold water, warm water, solo diving and towing divers in needs on my octo) as my instructor.
In all likelihood I also probably had more experience than him buddy breathing from a single reg assembly as well and all from my initial training...
Holding my breath...pretty darn hard not to do when swimming lapses (with and without snorkeling kit) underwater or doing the four bottles/eight swimmers circus in the deep end of the pool and having to swim from one bottle to the other...
In all likelihood I also probably had more experience than him buddy breathing from a single reg assembly as well and all from my initial training...
Holding my breath...pretty darn hard not to do when swimming lapses (with and without snorkeling kit) underwater or doing the four bottles/eight swimmers circus in the deep end of the pool and having to swim from one bottle to the other...