Disabling the recycle timeout settings in SSRS
It's recommended to let SSRS recycle periodically so it doesn't hold onto memory it no longer needs, which may be useful to the rest of your server, for example if your SQL Server instance lives on the same server (you wouldn't want SSRS bottlenecking the rest of your SQL Server instance).
If you are able to adjust it to a recycle frequency that happens off-hours that may be best, as noted in this article. Otherwise the correct value is 0 to disable it, as you mentioned. For more information, see this other article Adjusting the SSRS service recycle time to zero seconds.