At the end of your turn, you draw 2 Treasure cards. These can be evaluated together and need not be drawn 1 at a time. Many people play this way naturally and that was the spirit in which the rules were written.

That said, Flood cards should be drawn 1 at a time so players can respond to them individually.

karl... you are drawing the cards at the end of your turn... thus you have to get yourself back down to 5 if you go over... Otherwise.. if it isn't your turn and you get given cards that send you over 5.. well.. time to use that sand bag or helicopter or discard.. no saving until the end of your own turn.