Jason Brimhall has a script to determine when your databases have been backed up:
I have also set the script to accept a database name parameter. If a name is provided, then only the backup history for that database is returned. If the parameter is left NULL, then the backup history for all databases will be returned. Additionally, I added a number of days parameter to limit the scope of the report to a specific range of days.
Among the data points returned in this script, you will note there is the duration of the backup, the date, and even the size of the backup. All of these attributes can help me to forecast future storage requirements both for the backup storage as well as for the data volume. Additionally, by knowing the duration of the backup and the trend of that duration, I can adjust maintenance schedules accordingly.
These types of reports are quite useful. Aside from giving you useful information on database backups, it should also be a reminder to have a process which deletes older backup data over time so that your msdb database doesn’t grow to unsustainable sizes.