chess training during an OTB tournament

I heared that it is not good to train your chess during an OTB tournament...do you think the same ?

During means that in some days you play some rounds, in the break days you study some chess, etcetera...Will the training decrease your chess will and power ?

Is this including specific preparation on opponents ?

Originally posted by vipiu
I heared that it is not good to train your chess during an OTB tournament...do you think the same ?

During means that in some days you play some rounds, in the break days you study some chess, etcetera...Will the training decrease your chess will and power ?

Is this including specific preparation on opponents ?