This concept came up in the SSD data retention thread:
Most SSDs will let their cells rot away so this is very relevant to them, hdsentinel, badblocks, diskfresh and I think spinrite where all mentioned in the thread to refresh data on drives. Very convincing results can be gleaned from the thread on the performance degradation *most SSDs suffer from after having data at rest for more than a year or two.
I wouldn’t expect a magnetic annealing to affect a HDDs for atleast 2-3 decades assuming they weren’t operating in some kind of strong external magnetic field so this isn’t particularly helpful to them.
One of the reasons HDDs are so robust against magnetic annealing induced bitrot is that there is only an “off” and an “on” state, while SSD cells are commonly at 16 different charge states to store information; if HDD manufactures decided to encode data in the intensity of a magnetic bit on the drive then I would be much more worried about refreshing them.