Asking a question for each card helps you to set your intention for the very tarot reading itself. However, you can have your intention in your mind as you shuffle, draw all the cards and place them in the spread, and refer to the questions when interpreting the cards. I find that asking the relative question for the card position I am drawing helps to focus my energy and clarify my mind. But sometimes, I just hold the intention and draw the cards only to refer back to the ‘question’ when I am interpreting the card. It is totally up to you and whichever you feel comfortable with.