Hey Ryan, such an important question everyone wonders when learning a language. Unless they're making serious mistakes I'd rather let my students keep talking, no matter if everything is not down to a T. Once they've finished, then I make the suggestions and corrections. I've found this very useful for them rather than correcting them all the time, otherwise students may lose their confidence while speaking and being afraid of expressing what they want to say! :)

Well, I think it depends on the level of the other person. If it has a quite goood level and makes, let's say, 1 mistake every 10 minutes, I think the mistake should be corrected straightaway. Otherwise, if the level is very poor, you need to keep the conversation flowing. So the mistakes need to be told at the end of the conversation and giving general advices (as you should study more about the subjunctive mood, or you should pay attention about the pronunciation of the "v" in Spanish, etc.).

I think this is the rule of thumb, and at the end of the day every person is different.     

I think it's annoying to correct the other person each time he or she makes a mistake. That's why I prefer to write down the mistakes the other person make, and at the end of the conversation I tell the other person the right way to express what she or he meant. 

Language exchanges without corrections are not useful to me. Since my goal is improving my English.  

I agree with David M and Christina. I also think the language partner should express a preference on how they want to be corrected or improved. They may want to be corrected immediately or prefer to wait at the end. Personally,  I feel it is not useful to wait at the end of a few sentences for feedback unless the partner is already pretty advanced and makes few mistakes. For those lower level ability language partners,  you can actually do both methods. Get them to say a few sentences for the practice in speaking. And also speak individual sentences which are then corrected. Different methods for different objectives. Nobody ever said you cannot mix methods.

Hi Ryan. Personally, I prefer that the other person correct me every time I make a mistake. These are my reasons:

1. My partner tell me what is wrong and the proper way to say it.
2. If I my partner waits to the end of my speech, he/she neither remember the full sentence nor the context.
3. If I make a pronunciation mistake, he/she spells out the word so I can repeat it till I pronounce it adequately.