if I set a custom timeout on a parent resource does it apply to all child resources?

How do you set a timeout on a resource? Is it a property of the provider? Resources do inherit the opts of their parents, if not explicitly override. So if the timeout is a provider parameter, then yes, it will apply to child resources.

Timeouts are set this way: https://www.pulumi.com/docs/concepts/options/customtimeouts/

Right, so it's an opt. The general recommendation (or at least, my general recommendation) is to set the opts of all child resources to be the opts of the parent resources, unless you know better. As the docs you linked say, ComponentResource doesn't honour this, but you explicitly set the child opts this way, then each of the children will have the custom timeout. Which unfortunately means you could end up waiting (custom timeout x number of child resources) for everything to time out... but that's why I said "unless you know better" 🙂

I was afraid you'd say that. So much code to go through

The downside of configurability is.. having to configure 😞