Well, for some affectible reasons, the lead Cure gets the most center attention all the time, which makes the heroine more 'super' which makes them stand out more, and the reason behind the main course over the main setting of the story. This trend follows from 2008-2014 (excluding 2010 never has one) mostly is the story about them. However in 2015, this was all dropped to include all the main members with power-ups.
So I'm gonna tell you each of the Lead Cures' main roles.
2008-It was Nozomi's birthday celebrated
2009-It's about Love reconciling with an old rabbit doll named Usapyon she played as a child.
2011-Nothing much about Hibiki, but maybe her partnership with Kanade during one scene she got captured.
2012-Miyuki's love for reading stories, and the reason behind Nico and the fairytale world.
2013-Mana's future when she gets married, even her child memory of her late grandmother and her dog.
2014-Tsumungi's hostile with Megumi and her happiness reached her.
2015-Haruka making the pudding in one scene
2016-Mirai's close relationship with Mofurun
2017-Nothing else about Ichika, but it's mostly about Ciel's story with Jean-Pierre
2018-It's a crossover film, but Hana and Nagisa recall lost memories with their teamnates
2019-It's about Hikaru and Lala bonding with UMA they were there the whole time
2021-Nodoka making friends with Kaguya
2021-Nothing else about Manatsu, but's it's mostly Laura's story about her designed queenly role with Sharon in this one.
2022-Yui reconcilling with Cait Sith she met in her past.
That's just about it.