Reference:
https://www.citrix.com/blogs/2014/03/29/xendesktop-gslb-dr-everything-you-think-you-know-is- probably-wrong/

6 GB (heavy/scale) x 30 VM's per host = 180

https://www.citrix.com/blogs/2011/06/30/desktop-transformation-capabilities-assessment/ Users and Applications.Establish the pain points experienced by the user community by distributing a questionnaire to a representative sub-section of users. The characteristics of the user estate need to be established so that that the High-Level Design can be scaled appropriately. Therefore it's necessary to capture the following metrics:
Total number of users (available from the user segmentation phase)
Number of third-party users
Number of concurrent internal users
Number of concurrent remote users
In addition, identify the application delivery mechanism(s) currently in use and establish whether the applications have already been packaged.
Network Architecture. So that the High-Level Design can determine if there's sufficient network capacity, map the location of the users against the existing network topology. Review existing monitoring solutions for periods of latency, lost packets and insufficient bandwidth. Check that there are a sufficient number of IP addresses available to support the proposed virtual desktop solution. Also, examine the topology for single points of failure and potential bottlenecks as well as determining whether Quality of Service (QoS) and network optimization devices are available.
Training and Certifications. Desktop transformation projects should involve training for both support staff and end users. During the capabilities assessment, capture the current certification level of the support staff as well as their experience across the environment including Citrix, Microsoft, Storage, Networking, Virtualization, etc.
Virtualization and Storage. Perform a thorough review of the virtualization and storage solutions currently in use. Establish their resilience, scalability, performance and redundancy so that the most appropriate solution can be selected for the High-Level Design.

Note: Block inheritance can NOT be used and the VDA agent machines should received additional lockdown settings that are NOT being applied elsewhere and finally the CTX team needs to have the ability to test implement settings all that can only be done with Studio and WEM since there is an AD Team to do GPO's.