The guides are mentioned a few different techniques and features that can be used in different scenarios. A good answer would be that it depends on your requirements. For instance if you have a large and complex environment, you might need a cluster and a third-party NLB (Network Load Balancer) in front of the webservers, but some only use a single webserver.
It very much depends on what you need and as they state in the guide:
Please be aware that this document is not supported and meant only as a guide. Individual environments may require adjustments for things to work correctly. Recommend contacting QlikView Expert Services for help with configuration.