I knew about such periods from reading the handbook when I was working for a global company where US was 3-4 weeks depending on title and other locations were ~

I knew about such periods from reading the handbook when I was working for a global company where US was 3-4 weeks depending on title and other locations were ~3 months. From a practical perspective, how does that work? I understand if you’re making widgets on the assembly line, you’re gonna keep coming in. But if you’re doing creative work or close work with customers, isn’t there a concern that you’re effort will definitely flag and you’re gonna do crappy work?