Yes RIDX does work good to keep your septic system working properly.
I used RIDX at least every 6 months in the septic system of the house I used to live in and it worked great and it helped prevent backups of the septic system by breaking down waste faster in the septic tank.
You still need to have the septic tank pumped at least every 5 years but the RIDX can help keep the waste broken down to prevent backups.
You can add the RIDX once per year or every 6 months if you want too.