When 4-6 players are playing Phase 10 is it possible that the deck can be exhausted before anyone completes a phase?
Yes, we have had an instance where we made it through the draw pile without anyone going out. (There were 5 of us). We used to play a lot, so I think it's rare. We just took the discard pile (except the top card) and shuffled it to make a new draw pile. I didn't see this situation in the rules though, so it's unofficial.