Ok, first of all learn rsync or robocopy. But you being on Mac rsync should be your guy (My personal favourite). Those two will only copy the difference between A and B. Waay faster than copying back backup everytime and won't consume the disk as much.

Now that you know, rsync stuff into the microsd card can now become a daily thing, depending on your usage and how much change you have between sessions.

By sessions I mean whenever you work the data and the progressive difference between backups.

Now, about the long game. I've been using on my phones and tablet for at least 2 years swapping movies and music on them every few months and they still work.

I have another one plugged into the work laptop and slapped a VM on it because it was unused and decided to test how long before it breaks. 6 months into the test, 100 or more boots and still holds it.

So in the end I agree with the other comments, it depends a lot on how many times you'll replace ALL 1TBs on the microsd. That's what damages it the most, if you edit a few GB every month with rsync or similar you can try.