For students who are at an intermediate level, participating in a conversation table is a really good idea!
This is the opportunity to talk and put into practice what has been seen in a classic course.
For beginners and advanced levels the benefit is much less obvious.
A conversation table will not allow beginners to assimilate the basic structures of the language. As for the advanced, some may feel frustrated not to speak with native speakers and, therefore, not to improve their level.If your goal is really to learn a language, the conversation table will not be sufficient. Learning a language requires, in addition to putting into practice in a real situation, to be able to assimilate the different structures of the language.
Doing a little grammar and conjugation is therefore an essential step!
Note also that for beginners, a conversation table will be of little use. Difficult indeed to start and speak without any basis!