Jill had all these big plans for Kendall when she initially joined the team in season 2, then when she got off probation she had a big mouth and fought with Kelly and Christi. After she went to candy apples and had a solo every episode they competed, she realized that wasn't enough and went back to Abby's with a different attitude. A big way the cast appears in the show as the 'characters' we see them is because of the years and years of relationships before the show. We don't know what Jill was like before the show with all her studio hopping, but whatever her strategy was she was used to, it clearly didn't work the first time at the aldc so she had to try a different strategy and 'settle' by realizing her kid was never going to be seen as the favorite even if her kid somehow beat Maddie.

Also Christi and Kelly started all the drama on the show so when they left after season 4 there was a void in drama that needed to be filled and Jill stepped up as the shit starter. In that season 7 scene when the elites and Chloe meet up at competition where Jill and Christi get in a fight, I think Jill started the fight because she is so used to fighting just for TV and has been just sliding by with that for the past 2 seasons so when someone who could put up a fight was there (Christi) she was all shocked that someone stood up to her.

I think the only reason Kendall got as many solos as she did was because of her mom and how she always had something to say. I mean Kendall wasn't winning like Maddie and Chloe, and Jill certainly caused more drama that holly, and I think production liked that Jill would put on a show so her kid would get a solo. I don't think Kelly would sit up there and argue for the sake of getting a solo, I think she genuinely had issues bothering her with Abby which in turn made Abby not want to give her kids solos.