It is important to attend every single session as this allows you to avoid talking to anyone.
Do not turn your mobile off during talks because otherwise it will not be so obvious how important you are. If it does ring, do not feel obliged to leave the room.
Whilst indeed you should attend all the talks, it is most important that you do so with the right viewpoint; they are not for giving you new ideas, but rather to reinforce in your mind how superior your own ideas are.
Confer with people; open your mind, and maybe learn something new.