Yup, but running stability studies is also costly too, not so much for the testing, but for regulatory approvals - you need to write up the stability part again, argue why the results are still acceptable in case you see any increase of degradation products, and pay a fee and wait 6 months to 1 year to get it approved, then enjoy paying again to relabel all your package, PIL, etc... that goes with it.

Most of the time, unless you had a realllllly short shelf life at submission timing, the additional work is not worth it for the pharma industry side. Resources are better used working towards new/pending products.