At the office, we recently upgraded our staging server to PHP 7. For the most part, this caused no problems at all and worked very well (and faster!). But our event pages were failing, just giving us a white screen. I looked in the "Recent log messages," and saw this: "Error: Using $this when not in object context." The code that triggered this error was a non-static class method that was being called statically from within a different class. In PHP 5, this code only gives a "Deprecated" notice that non-static classes should not be called statically.
Have you ever run a PHP utility script on a Windows/IIS platform and had it unexpectedly timeout? Your IIS settings for script timeouts might be conflicting with your PHP settings.
Let's say your script is querying a remote, third-party web service for share data on 3000 articles on your site, and for whatever reason, the web service only allows you to query share data for one URL at a time. This could take a while. So on your Windows/IIS server, you set up a scheduled task to run at 1:00 am to retrieve all this data and put in your database for convenient access.