Yes, that’s the correct syntax. Once started, backups run until finished or stopped by error or administrator action. The backup window only affects the start time.
It may be difficult for all needed backups to start during your one hour window if the number of clients is large compared with the Max simultaneous backups on the Server tab, especially during the initial full backup series when more data is transferred. Note that any image backups are also counted in the number of simultaneous backups.
Another consideration is the Interval for incremental file backups which is expressed in hours. If the most recent backup for a client started near the end of the backup window, and you have the interval set to 24 hours, it may not get started before the end of the next backup window, causing a day to be skipped. To avoid this schedule creep I usually set the Interval to 23 hours so daily backups happen as close to the start of the window as possible.