How to know when to stop?

[Greg P.]

Hello, I'm working on a few rehabs and there's a lot of "iffy" problems that I could fix but would cost thousands more. For example, siding is going bad and painting will only cover it up slightly. Do I replace and make it brand new or do I just skip? Another example, roof looks just okay, no leaks, but it definitely does not look new. Please let me know your thoughts on how to know what to do and when to stop. Thanks!!