About Backup Window and Intervals

How the Backup Window affects the intervals?
For example, lets say my interval is every 5 hours, but my Backup window is weekdays from 3 AM to 3 AM and from 6 PM to 10 PM , when will my backups be taken?

Along the same topic, what happens if a client is OFF for a while and misses few backup windows, will the backup start as soon as it comes online, or it will wait until the next backup window?