We've had a bunch of iPhone 6 and 6 Plus repairs at our student repair center recently...all screens, of course. Even with cases, the 6 series screens seem to be incredibly susceptible to damage.
If you use the full front panel assembly, with camera and microphone, it's a pretty quick repair. It should take 30 minutes, max. We're trying to stock up on enough spare parts from broken screens to be able to save some money by assembling salvaged parts with just the screen and digitizer (not the full front panel assembly) ahead of time. It should save us about $30 per repair.
We were rocking along with these repairs and then all at once hit a major snag and were unable to get the cables back in. Each repair started to take over an hour after multiple attempts to attach the cables were a frustrating and fruitless venture. We realized that we had switched to using the spudger, not the iFixit Opening Tool, to try to attach the cables. The spudger is just not suited for the task. Once we switched back to using the iFixit Opening Tool, the cables popped into place on the first try.