The discussion method is time-consuming and tangental.

那种讨论方法既浪费与正题脱节。

His talk branched off from the subject.

他的话偏离了正题。

His mind kept branching off into the contemplation of silly things.

他总不能专心于正题而尽想着愚蠢的事情。

He talked a lot, but never really came to grips with the subject.

他了很多, 但是没有真正谈到正题。

Cut the waffle and get to the point.

别胡扯,谈正题。