Any attempt at changing the variable in the json (the cron timer) seems to be ignored and it continues just backing up every 30 minutes.

current config in ftbbackups2

"backup_cron" : "0 30 1,3,5,7,9,11,13,15,17,19,21,23 * * ?"

Trying to achieve backups every 2h. Seems to ignore the above and continue every 30m.

Try this website http://www.cronmaker.com/

It uses the same java library behind the scenes to generate the cron notations.

Huh. Incredibly odd, it decided to only update overnight? Anyway, this isn't an issue anymore? The above ended up working for every 2h. It would be neat to have a few suggestions in the config file though!

@ThePaul-T might want to change the link in the config file. At least in Direwolf20 1.18, the link is HTTPS but Cronmaker doesn't seem to support that (for whatever reason). I followed the config's link in Firefox and it looked as though the website was down.

Your HTTP link worked fine on the other hand, and is what ultimately solved my problem (though I still don't understand this scheduling format for the life of me)

Edit: Might also be worth looking for another website that works the same, but supports HTTPS in the first place. This is the main reason I haven't PRd a little one-character patch to ConfigData.java
follow-up edit: what about https://www.freeformatter.com/cron-expression-generator-quartz.html? It gives a lot more examples and has a more comprehensive interface in general. I'll open an issue about this so I stop editing this comment on a closed issue...