For me, when with a partner, it's both before and after. When soloing, it's usually before only, and not full insertion, which requires more contorting than I can comfortably do at this stage in life. The practical benefit of a well-lubricated rectum is obvious when anything is to be inserted. The erotic pleasure derived depends on the individual. Personally, I find a deep, persistent, bare-finger anal massage pleasurable in the extreme. I should add, when the massage is given by a person with fairly slender, well-manicured middle finger. It's so incredibly intimate! Of the three enema partners I've been lucky enough to have -- ex-wife, lady friend, and man of similar taste -- all have obliged me with "prostate massage", including while I was retaining an enema they had just given me! My ex-wife would compound the pleasure with constant eye contact, gently wiggling and working her finger and being incessantly verbal. She'd calmly "interrogate" me with questions like, "You know why I'm doing this, don't you? To make the point that I can invade your most private place any time I want", and "What did Mama have to give you for being naughty and disobedient? You know the answer -- begins with an "e". Those wonderful sessions pegged my lust meter, and thinking about them still does. A unique kind of erotic experience, thoughts of which never get old!