The first 90 days is usually enough time to weed out the lemons.
If the product doesn't fail within that time, it usually will live for the next 3~10 years, or longer, depending on what it is.
Anecdotally, a lemon Mobo, GPU, RAM, or SSD will die within the first 30 days, if it was not DOA. A majority of lemon parts will give the ghost within 10 days, if you stress test them. If the part survives 24hrs of stress testing, it'll be fine for at least 3yrs.
The most unreliable parts are usually RAM sticks, or Mobo RAM slots, followed by GPU.
With that said, I would avoid refurbs of anything with a screen on it.
That would be laptops, monitors, phones, and tablets. Usually they have a dead pixel, a scratch, or some other issue with the screen to get returned/replaced. The QC staff don't get paid enough to do a good and thorough job of checking the screen.
The only exception is if you can see it working in person, or it was a shop window display item.