Hello Giovanni
The maximum value has meaning only when backing up the configuration files locally. Configs are saved locally if the flash (or other local storage location such as disk0) is chosen as the path destination. This maximum feature is used to ensure that you are not going to run out of space on the local storage device as this is usually limited in size. In such a case, after the maximum number of files has been saved in the archive, the oldest file is automatically deleted when the next, most recent file is saved.
If the path you choose is a network path, that is, if you choose ftp, http, https, tftp, or some other supported network protocol, then the maximum number of archived config files is actually unlimited. Management of the storage space on remote network devices is performed on those devices, and cannot be enforced via the CLI of the IOS device. For this reason, the maximum cannot be configured when backing up to a network path.
I hope this has been helpful!
Laz