In Scrum you have Sprints (~weeks) and Releases (~months), and at the start of each you meet to plan User Stories and Features, respectively, that you want to a

In Scrum you have Sprints (~weeks) and Releases (~months), and at the start of each you meet to plan User Stories and Features, respectively, that you want to accomplish during those time frames. SAFe is a formalized version of Scrum of Scrums (multiple Scrum teams working together) and PI (Programatic Increment) is just another name for Release. So PI planning is release planning, but all the scrum teams have to coordinate dependencies (team A needs to complete story X in sprint 2, so team B can use it to complete story Y in sprint 3; teams B and C need to allocate time to design an interface in sprint 1 that they both use in sprint 2, etc), so it has more overhead. Ours started out taking three full days, and we eventually pruned them down to two full days which was still painful, but mostly productive. I can't imagine four whole days - day 5 would have to be dedicated to drinking.