I do the same (though not for personal photos, only for my professional wedding work). SD cards are small, I have a stack in a safe.
Every professional/paid client I shoot for, I do on new SD cards. I have dual slot cameras, so one card just permanently lives in my camera and gets formatted between shoots, the other I treat as a one-time use card.
Doesn't eat into my margin too much, and I appreciate the extra redundancy when dealing with someone else's wedding photos, so that if somehow something went catastrophically wrong with the rest of my back up process and off sites, at the very least I still have the SD card with the RAWs on it.
Gosh I hoped all wedding photographers thought to do the same...
You'd be surprised. I've seen and heard some real horror stories.
My $dayjob is IT/infrastructure ops, so backup hygiene is engraved in me as a core value. A shocking amount of people outside of tech have no concept of backups or redundancy.