I'd guess they use a hybrid approach ... the statement about iPhones always being on the verge of selling out is a red herring.
Whether you ship by air or sea, so long as you do it consistently, the number of phones you have available is a constant based on the rate you're manufacturing them. All the air versus sea argument does is change the lag in receiving them.
Assuming the rate they can be manufactured can be adjusted based on demand, you want to make sure you're always on the verge of selling out to avoid carrying more inventory.
So my guess is that they normally ship by sea but increase the manufacturing rate and ship some percentage of phones by air to keep the stores "just stocked enough".
Whether you ship by air or sea, so long as you do it consistently, the number of phones you have available is a constant based on the rate you're manufacturing them. All the air versus sea argument does is change the lag in receiving them.
Assuming the rate they can be manufactured can be adjusted based on demand, you want to make sure you're always on the verge of selling out to avoid carrying more inventory.
So my guess is that they normally ship by sea but increase the manufacturing rate and ship some percentage of phones by air to keep the stores "just stocked enough".