Time to Inframe?

[JimT]

There's lots of threads on here about specific circumstances that necessitate an inframe. But I was wondering, in a more general sense, what factors dictate that it's time to stop and do an inframe? I have my own specific concerns which motivated this post, but I'll address them in a different thread. The purpose of this thread is to serve as a one stop reference for all about what to consider when determining if an inframe is required now. Please list both specific factors (like broken parts, specific symptoms) and general limits (such as max oil consumption, max wear) that indicate the time is NOW. You can also include links to other threads that may go in to more detail about specific items. Again, this thread is meant to be a quick reference, not a how-to.