A best practice is a method, technique, or approach that is generally accepted because it produces better or more reliable, repeatable results. You can consider this as a standard way of doing some things. However, it's not a law that must be universally followed. Using best practices requires you to know the background of the best practice, and how it applies to your specific situation and design.
Anyway, best practices remain a useful pattern for the design of virtual infrastructures in a proper way; it is also valuable for validating the design itself, and provides compliance with possible future support feedback or requests.
You can find several best practices for VMware in different documents, such as the following:
- Performance Best Practices for VMware vSphere 6.7: https://www.vmware.com/content/dam/digitalmarketing/vmware/en/pdf/techpaper/performance/vsphere-esxi-vcenter-server-67-performance-best-practices.pdf
- VMware vCenter Server 6.5 High Availability Performance and Best Practices (no updated version available for vSphere 6.7): https://www.vmware.com/content/dam/digitalmarketing/vmware/en/pdf/techpaper/vcha65-perf.pdf
- VMware vSphere Availability 6.7: https://docs.vmware.com/en/VMware-vSphere/6.7/vsphere-esxi-vcenter-server-67-availability-guide.pdf
- Best practices for upgrading to vCenter Server 6.7: https://kb.vmware.com/s/article/54008
Remember that there are also vendor-specific best practices, such as for storage or networking (but also for servers). When VMware has a general suggestion (such as, in storage, the multipath choice), the specific vendor will usually have more detailed information for the configuration part. For this reason, try to apply the more specific recommendations based on best-practices, but always check that there aren't any conflicts between different recommendations.