Correcting Mistakes

I've been reading the JET teaching handbook and came across an interesting idea that I didn't consider carefully before. When engaging in a speaking activity, or even talking to people, it is not always a good idea to correct all of the mistakes while the person is speaking. The reason for that is that pointing out mistakes during the conversation makes the person worry about grammar/etc. as opposed to trying their best to communicate.

I guess it depends on the English level of the person as well as age (I think small kids would take it as a given that they are getting corrected, and it will likely not affect their motivation, but this is not the case for older students). Whether or not to use this method probably also depends on the level of students' confidence, as well as their goals. I think this is more applicable for lower level of the language knowledge.
One way to correct the mistakes that they suggested was making mental notes during the conversation, and then mentioning the major errors after, especially focusing on the group as opposed to individuals (if this is a group activity).

I am going to think and read more about this idea, and I'll try it out at school tomorrow.