We never discuss all plan-design choices, regardless of how much time we have at our disposal. Most clients don't want to know all the ins and outs, they want a plan that fits their needs and wants. I do have a few attorney clients who have read every single page of the document and asked a couple of hundred questions, but those clients are very rare.
The way I look at it, plan design is a service. I don't expect my clients look at an adoption agreement and tell me which boxes to check. Instead, I find out what the client wants (often with input from the CPA, adviser, and sometimes attorney) and I design a plan to fit those needs. I will then present that plan and explain why I designed certain sections the way I did. If the client wants something changed, we talk about why they want the change and whether it is the best way to achieve it.