Time Machine frequency on Mac Studio

Hello,

So I have Time Machine backups on our Mac Studio backing up to our
Synology DiskStation.  But now I'm puzzled.

It has the option to back up hourly, daily, or weekly.  Hourly is too
much, and daily is too little -- I'd like to back up every 6 hours.

Is there a way to set that up in the gui, or do I need to set up tmutil
jobs in crontab?  Or...?

Thanks,

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