Updating weekly or fortnightly is fine, but be sure to check for any news for manual intervention, and be aware that keyring changes need to be taken into account in case of verification errors (i.e. update archlinux-keyring if packages seemingly randomly fail to download correctly).
However, as has already been said, smaller, more frequent updates means there is less to download in one go, fewer changes to check in the case of pacnew files, and fewer packages to check in the case of regressions or new bugs.
Two other options are to pin your mirrorlist to the Arch Linux Archive server (so you can’t update until you want to) or to use my unofficial user repo that has daily and weekly (and associated deferred) update cadences.