Does macOS scheduling fail when it has been running for more than 10 days? Irregular backups suggest that it does.
cron
If the kernel is the heart of OS X, launchd is its brain. Use it to run periodic tasks such as synchronising folders automatically.
Macs are increasingly reliant on background services, and increasingly vulnerable to their problems. Mastering the services on your Mac will help make it faster and more stable.
The Eclectic Light Company 