Is Setting The Value Of Server.ScriptTimeout Enough To Prevent Page Timeouts

On an administrative page with a long running process we're setting the following:

protected void Page_Load(object sender, EventArgs e)
{
this.Server.ScriptTimeout = 300;
//other code
}

Is this enough that should prevent that page from timing out as it does what it needs to? I have no control over the process and how long it runs but we've found that 5 minutes is more than enough time, yet we're still getting intermittent errors of:

System.Web.HttpException: Request timed out.

We've tried upping the value to 600 with really no difference and in any testing we've done we can never get the actual process to run for that long. Is there elsewhere that we need to be setting timeout values that won't affect the entire application and only the specific page we need the longer timeout value on?