Quoting from VMware's Virtual Desktop Blog 

There are several approaches or strategies in attacking your VMware VDI desktop deployment from a design standpoint. Most organizations enter their architecture with hesitation and reserve using a very static approach. They plan to map desktop users 1:1 each desktop user will be given a dedicated virtual desktop and some division or swag is made regarding how many desktops they can concurrently run on each VDI server.

Really there is nothing wrong with that. Probably one of the most difficult tasks in planning a desktop migration, particularly when moving from a distributed architecture to a centralized architecture; is profiling your users,
understanding the desktop compute cycles they need, and centralizing that in a fair-share scheduling model. Because of the difficulty and effort required in looking at every user across the enterprise and coming up with a
methodology that makes sense and getting the design right out the gate. I am a fan of getting sets of common users onto a VDI architecture, then studying their usage patterns.

Ultimately a static 1:1 approach is not going to yield the highest return on your dollar. The more dynamic you allow the architecture to become. The higher return you will realize. Often when I meet with customers and discuss their VDI architectures I talk about the concept of oversubscription. Oversubscription is stepping outside the bounds of asking how many desktop users per core can I get, and really understanding your user’s usage patterns, and figuring out how many more users can I allocate get per server by oversubscribing. 

In most enterprise and office environments, as you walk around you will find large populations of empty cubes and idle desktops. Business is constantly changing and in order to stay competitive companies are being forced to change the workplace. More people are teleworking, using flexible work schedules and becoming more mobile. When users are in two hour long meetings or on conference calls several times a day, typically they are not using their desktops. When three out four people are not working on an exact 9-5 schedule the number of concurrent users is reduced. All of this combined results in an opportunity to revisit going beyond static VDI architectures making them more dynamic and oversubscribing the servers. With this approach mileage may vary in different cases. For example, a contact center environment where users are heads down, might not realize the same benefits.

Read the rest of this blog post on VMware's Community, here.