Hi,
The limit cannot be increased beyond the maximum. If this is caused by having multiple updates and they cannot finish in the specified window you can create multiple maintenance window that run one after another. That way the updates that were not installed on the first run will be installed on the second one. If the server that you are updating does not have sufficient resources and that is causing for the updates to not install fast I would suggest to increase the resources of that server. If this is caused by any other issue I would suggest to provide more information about the issue as there are no details.
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