Generally, most fuel would be stored in bulk for the reasons given. However, on operations, bulk fuel has considerable transport and safety problems associated with it. It is much easier to decant it into jerry cans and issue the jerry can with fuel as a single unit, receiving back empty ones in return, which are in turn, refilled.
Generally, we tended to store unfilled jerry cans on pallets, one or two levels high. Filled ones were stored on pallets only one level high. Bladders were stored on the ground, surrounded by a low bund, about two feet high, to direct leakages and to prevent the spread of burning fuel.
I've served on refuelling points where decanting occurred. We were issued with gasmasks and relieved every four hours, otherwise we became "happy" from the fuel fumes and a danger to ourselves and the fuel depot. All cigarettes/lighters/matches were confiscated at the start of a shift. Once you were off shift, you were directed to the showers and given a change of uniform, to prevent skin problems from the fuel soaking into clothing. It was not my favourite or anybody else's duty, I can assure you. Even Ammo point was preferred.