The problem is that all parenting methods are about character development, anyone who has chosen to have DCs must have had a long term view of the type of adult they want to produce. I agree that when you are stressed, haven't had a lot of sleep etc then you may just want short term compliance, no one is a saint. However, most of the time, a responsible parent is looking to the long term.
I want self confident DCs who don't feel that they need to follow the crowd, who question things, who feel secure and loved, who are kind, caring and sharing, who are not afraid to make mistakes and learn by them and are imaginative, self reliant and honest. (I expect that I have left a lot out.)
To get a fully independent adult with all those qualities I have my methods and they depend on my personality, the situation, the wider environment and the personality of the DC.A book can be a guide, but nothing more.
Everyone is different, I think that people would recognise that adults respond to things differently and DCs are the same. I think it is madness to say 'this is the best way to treat DCs' or 'this is the best way to treat a baby', you can only say 'this is the best way to treat that particular DC'.
The reason that I am somewhat against UP is I would say that is more or less what my parents did and since I was a sensitive DC and a very reasonable, people pleaser I picked up on all the body language and the things they were not saying and I fitted in.
I don't have anything against it, just that you shouldn't kid yourself that you are not manipulating things your way. Of course parents have an agenda, they wouldn't be very good parents if they didn't.
I have never offered rewards before things e.g. exams, I have just said that 'you can only do your best' however I have, on occasion, celebrated afterwards and if they have done well I am pleased and I don't see the harm in saying they have pleased me, they know that my love is unconditional and I am there for them whatever.
Rewards and even bribery (as shown in an earlier post with dentist)have their place and so can punishment, e.g. if you break something you pay for a new one.