When on the bubble, or in the money, it is often in both your best interests to check it down improving your ods of eliminating someone. However, if not ITM then there is no need to check down.

BY suggesting you are obligated to check-it-down, she is suggesting colusion, which is cheating. So she is wrong. Texas holem is not a team game and you are welcome to play your cards any which way you want.

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If you feel you have a question, dont be lazy; make sure you have asked yourself first. Then search the forum, then just fucking google it to get as much detail as you can. You may then seek clarification on specific points from others.