Smart Backup provides management and automation of SQL Server backups (from on-premise and Windows Azure) to Windows Azure storage. With Smart Backups Microsoft takes regularly backups to Windows Azure of your databases or your whole SQL Server instance, whenever it is necessary.

This means you should define how long it should take until your database is online after a crash/disaster recovery, and from that period of time you should derive your backup strategy. But with Smart Backup you are just doing it the opposite way. Also not really recommended.