GPO Enforced Precedence

Solution 1:

I wrote about this here: http://myotherpcisacloud.com/post/2012/08/14/GPO-Application-Precedence-Just-Because-You-Can-Edition.aspx

TL;DR - The uppermost or parent GPO that is also enforced will win.

From Microsoft:

You can specify that the settings in a GPO link should take precedence over the settings of any child object by setting that link to Enforced. GPO-links that are enforced cannot be blocked from the parent container. Without enforcement from above, the settings of the GPO links at the higher level (parent) are overwritten by settings in GPOs linked to child organizational units, if the GPOs contain conflicting settings. With enforcement, the parent GPO link always has precedence. By default, GPO links are not enforced.

EDIT:

See here as well: GPO provides unexpected value

There it specifically states:

The Enforce setting is a property of the link between an Active Directory container and a GPO. It is used to force that GPO to all Active Directory objects within a container, no matter how deeply they are nested. The settings within a GPO that is enforced override other settings that would prevail because they are applied later. If there are conflicting settings in GPOs that are enforced at two levels of the hierarchy, the setting enforced furthest from the client prevails. This is a reversal of the usual rule, in which the setting from the nearest-linked GPO would prevail.

Solution 2:

Ryan (and I :P ) answered the question on how 2 or more enforced GPOs are handled, but I wanted to clarify that while GPO3 linked to the site will "win", the OPs sequence of how they are applied isn't correct.

The OP states:

Now my understanding would mean they would apply in this order, from the first to apply to the last to apply (thus the one with most precedence).

GP01 -> GP04 -> GP05 -> GP02 -> GP03 (meaning 3 has the final say on any duplicates)

Remembering that:

As far as the sequence goes itself (including enforcement, but specifically the sequence order that the GPOs are looked at when processing):

GPO3 (with any of its settings enforced and taking precedence from here on out)

->

GPO1 or GPO2 (depending on link order at the domain level of these 2, with GPO2 being enforced except where GPO3 settings overrule because GPO3 is enforced at the site level)

->

GPO4 or GPO5 (depending on link order at the OU level of these 2, with GPO5 being enforced except where GPO2 or GPO3 settings overrule)