Did the Singapore trip thru Tokyo to Singapore. CO to UA pre Star. There were issues there too but nothing I'd be blaming on anyone. The gates were pretty far apart. Coming back same way I had no boarding pass for my CO flight and had to go thru "security" without one for my CO flight. Luckily they didn't hold me up. Had to pick it up at the CO service desk. Anyone scheduling less than 1.5 hours (maybe more) between flights is gambling that there will be no confusion getting from one gate to the next, you won't be needing to take a shuttle, security won't be an issue, etc.