We did some carrots in 3rd because I felt like the demands were insane and she should be rewarded if she succeeded. Now...I struggle a bit more with it philosophically. I believe in carrots when you are being asked to do something inherently unpleasant or unreasonable. IDK. It feels a bit oogy to me at this age and stage. But I guess it depends on how "natural" vs. staged and paid they are.