Bitcoin Core – Is it wise to back up chain state/ and blocks/ only when Bitcoin Core is not running?

Here’s how to back up your Bitcoin Core data directory to save future sync times.

#!/usr/bin/bash

local_d=/root/btc_db

rsync -av --delete chainstate "$local_d"
rsync -av --delete blocks "$local_d"

Sometimes backing up to a remote location takes quite a while, so there can be a lot of blocks delayed in between. rsync -av --delete chainstate "$local_d" and rsync -av --delete blocks "$local_d". Does Bitcoin Core sync smoothly? bitcoind -reindex finish, feeding time chainststate/ Backups corresponding to different block heights blocks/?