Key here will be your time management: come in with a plan of how you will use your time. When I was preparing for 1h written cases for example, I'd have the following time objectives:
- 5 minutes to read the case, make sure I understood and build a structure
- 15 minutes to scan the data
- 15 minutes to build the story
- 15 minutes to create the slides
- 5 minutes to draft the recommendation
- 5 minutes to rehearse the presentation outloud
You get the picture...