In a story featuring a serious disciplinary spanking (often more than one of them), pretty much my favorite to read or write, I prefer to have it start out hurting quite a bit, then have the intensity escalate along with the sting and burn to the recipient's rear end.
Likewise, the victim's reactions ideally also become more energetic, starting with squirming, squealing and yelping, then sobbing, kicking and crying, after that bawling and blubbering with the scorched derriere dancing (especially under a caning or switching), finally if it's a truly severe and extended ass-thrashing the spankee ends up emotionally 'broken,' thus being reduced to mere moaning (possibly with each stinging impact) and whimpering before it ultimately concludes. (Of course, the coloration of the targeted bare behind changes also, potentially ending up glowing a deep maroon for a high-severity chastisement, but at the least "shining like a stoplight" with a fire-engine red hue.)
While my real-life seat-smackings (which are playful yet fairly intensive) usually result in my entering 'subspace' so that they eventually become considerably more enjoyable than hurtful, I rarely describe that outcome in my own stories, notably since I favor writing about strict corporal correction as opposed to erotic/fun spanking play.
Any bare-bottomed protagonist of mine can generally expect to end up with a blazing, blistered, throbbing posterior--fantasy as opposed to reality.
"Are bears Catholic? Does the Pope defecate in the woods? Well, ask a silly question about whether hineys hurting is a key element of the spanking kink's literature..."

--C.K.