Joking aside: You can schedule automated backups every other month using Google Takeout.

By scheduling you mean schedule a reminder to do it by hand?

No, it actually supports automatic backup and can also upload to third party services like Dropbox.

There is an explicit exception to the GDPR for duplicate/unreasonable requests.

It could be arguable whether monthly data requests are duplicate or unreasonable though. Anything more frequently, sure, but 1 month?