Engine management theory and airplane mixture leaning tends to be briefly discussed during pilot training and yet it is important to know how to use the red mixture knob during taxing, climbing, cruising and approaching to land. However, this is a subject that tends to be both confusing and often debated.
Hence, Brian has posted a very detailed entry about the subject on his flying blog and he has also included a fairly thorough list of web links to other resources. However, at the end of his entry, Brian also concludes that:
Once again, it is your choice on how to operate your plane. I am still exploring and learning. Talk with your mechanic, instructor, and others and form your own opinion. There are lots of opinions on this, and they seem to be in flux these days.
Again, this can be a fairly complex subject but Brian’s post provides a thorough explanation of it to help pilots form their own opinion.