alt Hacker NewsOnce a month might be too high because HDDs are rated at ~ 180 TB workload/year. Remember, the workload/year limit includes read & writes and doesn't vary much by capacity, so a 10 TB HDD scrubbed monthly consumes 67% of the workload, let alone any other usage.
Scrubbing every quarter is usually sufficient without putting high wear on the HDD.
A scrub only reads allocated space, so in your 10TB example, a scrub would only read whatever portion of that 10TB is actually occupied by data. It's also usually recommended to keep your usage below 80% of the total pool size to avoid performance issues, so the worst case in your scenario would be more like ~53% assuming you follow the 80% rule.