We were too harsh and not reasonable at times. And there was a period of pure abuse. There probably was also times when we were too weary to be consistent and tough enough, but I think lack of understanding was more harmful.
For me and husband the gut reaction tended to be give consequences, punish etc. and even when we did know better, it felt backward to reward badly behaving child. And of course when you did that, you got a bad eye from everyone else. Even when we absolutely knew that positive reinforcement was that was giving us some results and handling out consequences was just jamming things worse, it took quite a lot guts to reward screaming, kicking child that spits and claws in public for actually getting to his feet and ignore the unwanted behaviour. When tired it was at times simply too much to take all that pressure from others and not to go to consequencing, yelling or threatening.
And often we lost our faith on progress that was made and felt we simply needed to be harsher, because that just is, what you do when your child misbehaves.
The consequence of being harsh was lack of trust from difficult child's part. He felt we didn't hear him or were not in his side, so he had no reason to confide us. And that was part that ended up hurting him. His biggest current problem is PTSD and all the pesky little issues that brings with it (of course he also has his social skills and neurological issues.) While it is true that the incident that triggered PTSD was probably not preventable by us, it was so humiliating by nature that telling anyone would had been a long shot anyway and he was also sixteen at the time, and being much behind his chronological age in biological age, he was being hight of puberty and everyone knows how pubescent boys are with confiding to parents, so him not telling us about it, and giving us a possibility to try to prevent issues PTSD has caused him; it is also true that he would not probably been so prone to PTSD had he not have previous trauma history and that was something we should had been able to protect him of. If he would had trust enough to tell us anything what was going on in school. Instead we inflicted more trauma to him.
While difficult child has always been very loyal to us, we didn't give him much reason to believe we would be loyal to him. From his point of view we were always taking other people's side against him. Part was of course unavoidable because his perspective was often simply flawed. But even when we maybe were objectively in the right, it was his perspective that determined how much he had reason to trust to us.
To be fair, he was a difficult child and we were desperate. His lack of rule following caused us real anguish. When you are standing on river bank (and not the first, but second time) in endlessly cold and grey day and watching firefighter's diver team drag search that grey water of the river and a police officer brings you a wet coat similar to your child's that has been picked from the river and you just want to deny it could be his, but can't when you see your own handwriting in the tack with your kids initials and everytime when diver comes up, you can't breathe before you see that sign, that nothing was found. And then you wait for the next one. They are long, long hours, believe me. And after experience like that you are kind of ready to do anything to make him stay where he is supposed to be and under adults' watchful eyes. (No, that time he wasn't in the river, not that time, never got a straight story out of him how his coat was there, or where he was.)
That was what got us to try commando parenting. We just needed to have him in the school. Not bolt and run away and be who knows where days after days. We stripped him from every privilege, all the freedom, everything positive in his life. Took all his stuff, door from his room, took him out from sports etc. and everything was depending on staying at school. He got worse. We were 'picking our battles and not loosing those' and upped the ante. And somehow got so caught to this battle of wills and we totally forgot that our son is fiercely over competitive and prone to get stuck and not being able to give up even when he absolutely needs to. And that he can provoke anyone to red hot rage in matter of moments when he puts his mind into it. He got worse, we upped the ante and after few merry go rounds of that our attitude to him was getting increasingly insensitive and competitive and less and less emphatic. And when we had nothing left to up the ante with, we tried spanking. difficult child got more and more provocative and badly behaving and we were way too stuck to 'not letting him win' and our negative thinking of him that all became to full stop to a emergency room waiting room, where husband was sitting and waiting if the hospital social worker would come to talk to him and tell him that they had taken difficult child in for child abuse investigation and called police or would difficult child come out from the examination room and come home with him. difficult child, like any abused child, was fiercely loyal to us, and lied his little black and blue hiney off to the doctor who committed a serious professional misconduct and didn't make a full check up to a child with almost classical abuse injury in his upper arm/shoulder. And she really wouldn't had needed to do more than make difficult child take off his clothes and difficult child and easy child would had been taken into care and husband would had ended to court with child abuse charges. Can you imagine the thoughts and feelings we were going through the next night when husband and I were sitting on the floor both sides of the door of difficult child's room and staring the wall on the other side and listening difficult child to breath in his sleep. I probably don't need to tell you, that that trial of harsher methods in battle to make him stay at school ended then and there.
Not that we got him to stay at school with positive methods either.
We of course paid the price of all that in our relationship with him and his ability to trust us. And that price ended up being way too high.
Surprisingly he still is very loyal to us, and what you Americans would call loving I guess (all right, calling difficult child loving would cause the bigger burst of spontaneous hilarity than difficult child's Fb status from couple a year ago where he told about perfect free Sunday with cuddling with his girlfriend and watching movies; none of his friends was able to imagine the word cuddle and difficult child in same sentence without negation, 'loving' would be even more incomprehensible; but he kind of is

He just doesn't do warm and fuzzy.)