The more experience you have the more you're used to these things happening. I don't have to know that a specific thing might go wrong but I'm used to there bei

The more experience you have the more you're used to these things happening. I don't have to know that a specific thing might go wrong but I'm used to there being some random bullshit (weird CI, library happens to be deprecated, version inconsistencies, data turns out to have a fatal flaw, licensing, whatever). You can't plan for everything though, and you're right this is where a good PM helps. But then again this is all just estimates. The better you can estimate the better you can plan.