Is 1TB of cache enough?

[SylverCheetah53]

I have 4TB SSD. I am using 2TB for HDD cache.
I have 20TB HDD + 18TB HDD.

I was wondering if maybe 1TB could be enough, because I could use that 1TB extra SSD.
Thank you!

[Support]

Cache size depends on how much data are often accessed from your target drives. Generally, we suggest the cache size is 20% or more of the capacity of target drives.