About fractionation

[DarkKnight]

So I have been reading some Alek Rolstad articles (which are great, I really like your in-depth style of writing). A topic which has intrigued me more and more is fractionation, I am still struggling with conceptually understanding it, while simultanously realizing that I have been fractionating by push-pull I guess?

So what I wonder is, how many of you use this technique and can you share how, so I can maybe understand the dynamics of fractionation better.