the most important thing is that it's safe.
If you're using Bitcoin Core as a hot wallet, there's always the risk of online attacks. My advice: keep only amounts you're willing to risk in hot wallets (for daily use), and keep the rest in cold storage.
Also, make a few backups. I prefer different brand USB sticks. And once in a while make a new backup to include newer transaction labels.
Yes, thanks for your suggestion. I'm also planning to buy a hardware wallet in the next few months. Because I'm still in the bitcoin saving stage and currently don't have much bitcoin.
But I also started to think twice about using Bitcoin Core because the synchronization process takes a lot of time. It might be easier to use electrum. Does using multiple USBs also require having bitcoincore data on each USB?