Yes, it is highly recommended to place /var/log on a separate Btrfs subvolume when installing Linux.
In fact, this approach is the default setup for many Linux distributions (like openSUSE) that utilize Btrfs as the primary filesystem.
Placing /var/log on a sidecar subvolume provides several key benefits:
    * Efficient Snapshots: System-wide snapshots are an incredibly powerful Btrfs feature. By isolating /var/log (along with /var/cache), you can take snapshots of your root system without bloating them with hundreds of megabytes of constantly changing, redundant logs.
    * Debugging After Rollbacks: If your system breaks and you have to roll back your root filesystem to an earlier state, a separate /var/log subvolume ensures your logs remain untouched. This preserves the error logs generated before the crash, making it significantly easier to diagnose what went wrong.
    * No Snapshot "Bloat": Because logs are appended rapidly, including them in snapshots increases file system fragmentation and requires far more disk space to maintain previous states.
What to Keep in Mind:
    * Package Databases: While separating /var/log and /var/cache is universally recommended, do not put the entire /var directory on a separate subvolume. Crucial files, such as the rpm database in /var/lib/rpm, need to stay on the root (/) subvolume so they are included in system rollbacks.