I have noticed that often when people are singing and playing the guitar they pluck a base string then pluck strings with their index, middle, and ring finger. They then pluck another base string and then three stings again. Do you always pick the three stings under the base you are plucking or do does it change with the cord you are playing? Do you just pluck the base and then pick the three stings and then a base again or do you pluck the base and then pick three stings and come back up?

Thanks
Joel