There's a long thread on FT about a family stuck in Italy for literally over a week trying to use Buddy Passes.

I'd only attempt to use these when timing was not an issue at all, and I could afford several days extra lodging, felt comfortable scheduling my own trains/flights to other gateways, etc.

My brother-in-law works with many pilots, and is always offered buddy passes. My sister flatly refuses to ever try to use them after several very stressful experiences.