I think it would introduce a huge amount of legal liability to guess that a drug would survive on a shelf for 10 years based on 6 months of testing. Especially if it's something critical like an EpiPen or cancer med.
At the end of the day, there's no really reliable way to speed up time, and it would be a waste of time to add 10 years to a drug development timeline just so you can leave it on a shelf for 10 years to test if it still works.
And yeah, we could probably go through and retroactively test some Ibuprofin, but also remember that these drugs are repackaged / reformulated slightly every couple years for various reasons, and without a lot of legal protections, no company will consider it worth it to guess about drug lifetime.
At the end of the day, there's no really reliable way to speed up time, and it would be a waste of time to add 10 years to a drug development timeline just so you can leave it on a shelf for 10 years to test if it still works.
And yeah, we could probably go through and retroactively test some Ibuprofin, but also remember that these drugs are repackaged / reformulated slightly every couple years for various reasons, and without a lot of legal protections, no company will consider it worth it to guess about drug lifetime.