Would you still attend a training session if you believe that you don't need it? Why or why not?

yes always willing to learn new ideas.

 Why not I still learn from other people's "mistakes"

You can always be surprised. And you can still learn from other people's "mistakes"

I can always learn something new.

I must attend! I should not presume that I don't need training anymore. For the quality of learning I impart and get in return, is simply the product of all the training I have attended. I am  Judo instructor, a singing coach, and a Sport Scrabble coach. I  just do not train my players and athletes,  I train and play with them.  Commitment to a certain training, which I believe,  very essential is  compensated and is rewarded with an outstanding learning outcome. Only by training, one becomes champion.  A well trained teacher always dominates the fight.

 I believe that despite I have enough knowleged  learning of new things is more better to enhance our recent idea it will help us more competitive.

Yes 

its good idea to learn new thing all the times.

A participant is getting skills & knowledge to attend every kind of training, If any training is not need to be attend but if you have spare time then you must attend it to improve yourself.

If you have some urgent works and you want to save time, you can request to cancel it. 

Must attend training even you believe you don't need. it will help to build up more confidence and fill the gaps with which you might not be known.