Not only was it a chance for participants to test out their newly learnt skills, it was also a chance for them to experience sparring with a partner they haven't met until now. After all, giving everyone the chance to interact with each other is one of the objectives of the Extended Session.
It's kind of like speed-dating, but with the necessary protection in place. No pun intended.
Sparring practice in Ashihara Karate follows the idea of 'Fight Control', where there are no set rules of engagement as usually seen in tournament-style practice. Everyone is free to practice any technique they like, as long as they watch after each others' well-being.