My buddy's shop had a spindle crash last month from a worn taper they kept putting off. Jordan's point about time is fair, but that mess took three days to fix.
Back in 2019, I saw a similar taper failure at a shop I worked with. I used to agree with Jordan that running parts until they broke saved time. But watching a spindle crash like your buddy's changed my view. That single incident led to four days of downtime and over five grand in parts and labor. Now I see that a twenty minute check every month can prevent all that. It's a no-brainer when you add up the real costs.