I've found templates most useful as personal shortcuts.

I.e., once you've settled on a prompt that you may reuse, save it to something like a snippet manager so that you don't have to type/speak the whole thing again.

I've been doing this with a snippet manager that supports string interpolation. Recent example:

  I'm working on an ASP.NET Core Razor Pages web application that I need your help with. I will send you the relevant code over several requests. Please reply "continue" until you receive a message from me starting with the word "request." Upon receiving a message from me starting with the word "request," please carry out the request with reference to the code that I previously sent. Assume I am a senior software engineer who needs minimal instruction. Limit your commentary as much as possible. Under ideal circumstances, your response should just be code with no commentary. In some cases, commentary may be necessary: for example, to correct a faulty assumption of mine or to indicate into which file the code should be placed. Code: {{Code}}

There's obviously nothing magical about the wording; saving it just gives me a quick shortcut for inputting paginated code and then explaining what's needed.