Field Update + Update Records + Apex Trigger = ?

While the "Triggers and Order of Execution" page in the Winter '16 Force.com Apex Code Developer's Guide gives good information about the high-level order of operations, developers reading it are still unclear about how complex interactions unfold across objects that use workflow rules, Apex triggers, and Process Builder ("PB") processes.

Let's take a relatively simple set of automation applied to a single object:

• A workflow rule with a field update
• A recursion-enabled process that updates the record which starts the process
• An Apex trigger

When a transaction is processed, how many times do each of the above automation components execute in that single transaction? The answers below may surprise you/

Component Type	Num Executions
Workflow Rule	1
Process	6
Trigger	8

The exact step order in which the components were executed is illustrated below.

Workflow Rule	Process	Trigger
		1
2
		3
	4
		5
	6
		7
	8
		9
	10
		11
	12
		13
	14
		15

The takeaway should be that developers ought to be very careful when adding automation to an environment that uses "all of the above", meaning workflow rules, processes, and triggers.