...when they don't do as they are told.
Little girls get spanked when they don't do as they are told, for several reasons.
It's a punishment for not doing what they were supposed to do in the first place, for either thinking that they knew better than the one telling them what to do, subsituting their judgement for the one giving the orders, or because they were lazy, careless, or were thoughtless and forgot.
Being lazy, careless and forgetful are just as bad as outright defiance as it means the naughty girl didn't care enough about the one who told her to do something, to respect her enough to do as she was told.
So a hard spanking is needed to remind her that she Will do as she is told, when she is told to, as she is told. No exceptions.
And, lastly, they get spanked when they don't do as they are told, besides as a punishment for past misbehavior, but to also give them something to remember for a while whenever they sit, about what they did, and what they are going to do different in the future to avoid more such spankings.
Can't sit down Sunday :(
22 hours ago