I realize the primary objective with airless is to keep out oxygen, but when is that deemed either essential or extremely helpful?
The reason I ask is that there still seem to be a number of products on the market where one would think the manufacturer would have put this to use already, such as with Skinceuticals's vitamin C serums, and at their price point, I assume they either do not want to abandon the "prestige" of using glass packaging, or they found little benefit to spending a bit more money to go airless, even when it comes to products where the foundational ingredients are very prone to oxidation.
Some source online claims that it can extend shelf life by up to 15%. That is definitely good, but -- if true -- not exactly a game-changer, in my view. Does this 15% sound reasonable to the experts on here, or are many of the view that airless makes a radical difference with respect to preventing oxidation?