ECU Logger rate

I am using an Autronic ECU on my Subaru. I have my wideband wired in so I am able to log AFRs.

My question is what kind of AFR fluctuation should I expect to see if the logger is recording 20 samples per second?

Current logs show AFRs jumping around from about 11.0 : 1 to 11.7 : 1 (and everything in-between) within a one second sample.

Autronic offers logging sample rates from 100/sec to 0.2/sec so I don't think 20/sec is too defined, or am I wrong?