When does a TOGAF ADM Cycle start - what initiates it?

I am trying to understand TOGAF and mainly the ADM for a university Project. After reading up on the TOGAF documentation I was left with a quite basic question.

When does a ADM cycle start - what does initiate it? While the first run might by simply triggered by the decision to use TOGAF for EA-Management what is the trigger for executing it again and again?

I hope you understand my Problem.

I could say the Request of Architecture Work is the one that initiate one cycle of the ADM, this document is being created in the preliminary phase. Requests for Architecture Work typically include:

• Organization sponsors
• Organization's mission statement
• Business goals (and changes)
• Strategic plans of the business
• Time limits
• Changes in the business environment
• Organizational constraints
• Budget information
• financial constraints
• External constraints, business

From the book.

This is a document that is sent from the sponsoring organization to the architecture organization to trigger the start of an architecture development cycle. Requests for Architecture Work can be created as an output of the Preliminary Phase, a result of approved architecture Change Requests, or terms of reference for architecture work originating from migration planning.

Here in the preliminary phase we decide which are going to be the frameworks that made us develop and deliver our enterprise capabilities, and here in this phase we could select TOGAF as our architecture framework, this is why the preliminary phase is not in the ADM cycle.

What is the trigger for be executed again and again.?

I consider two triggers, the first one is the needed of the enterprise to develop other capabilities. The second one is a change request, depending on the scope of this change we will require to initiate another ADM cycle.