MUST you lay down your phase as soon as you draw the cards to play the phase? If you know someone picked up cards from the discard that will be able to play on your phase and go out do the rules allow you to hang onto the cards until you can lay down and potentially go out all in the same hand? Of course the risk being that the ofher player goes out anyways and you are stuck with all of your cards and don’t move forward.
Judging by the context and language used in the rules there are many places that say a player MUST do something but in this instance it says a player “may” which leads me to believe holding onto the cards is allowable.