Thoughts on purging

I have heard all different opinions on purging cigars. I had a friend tell me if I need to relight a cigar, to purge while torching the foot. I've seen someone else purge several times throughout their cigar. One friend is convinced his cigar tastes better if he purges several times immediately after lighting up (even using butane, which has always never imparted a taste on my cigars).

I'm interested in hearing what different people's opinions are on this.