Global RIFs require careful planning and implementation.
What can be achieved in a day (or a couple of months if WARN applies) in the US can take months (and yes, sometimes years), once taken global. What in the US can be implemented at no cost or with separation payments that can be enshrined in releases is often far more expensive due to statutory obligation internationally.
But, global RIFs are manageable if carefully planned. Here is a checklist to guide that planning.