The concept behind the punch in/punch out recording technique is relatively simple. When you have an almost perfect take but there are a couple of wrong notes here or there, why should you re-record the whole thing again when technology allows you to focus on the “offending” passages by starting and stopping the recording right when you need it.
Back in the days, using this technique was pretty risky because it meant you had to overwrite whatever you had previously tracked. Fortunately, nowadays every DAW worthy of the name comes with a much more simpler punch in/punch out function.
Read more about this here: https://en.audiofanzine.com/recording-mixing/editorial/articles/punch-in-punch-out.html