Forget using an SD card.
Install either Syncthing or Resilio Sync on both devices (or your phone and PC, which is what I do) and simply let it sync the folders you want (for Windows use SyncTrayzor, Android use Syncthing-Fork, iOS use Möbius).
They’re both robust and tolerate network disconnects fine, can be confugured to use only WiFi.
Best part, if you sync important folders to your PC, you always have that stuff, and new phone can just sync from there (which is faster and not dependent on old phone being on or even existing).
Syncthing is better on battery in my experience, Resilio is a little more robust but requires more RAM while running as it keeps the sync index in memory.
I use Syncthing on all mobile devices, any photos sync to home nearly instantly, other folders are set to sync only on WiFi or charging, depending on size and importance. It hardly affects battery after initial sync.







Yea, we’d need to filter out the behavioural angles to clearly identify causal relationships.
Do people who live longer just happen to start eating differently etc.
For example, the better I feel, the better I eat. It’s not the bad eating that makes me feel bad - the better eating is a consequence of feeling better.
I can tell exactly when my diet is going to tank, when my chronic conditions flare. Diet has zero effect on them.