As a sub, I've used Kahoot per teachers instructions. I have also used it when there is time left in class and to assist students in prepping for an upcoming test.
Kahoots are a great way for students to review topics! You can use any kahoot that has already been created AND you can make your own to better fit the topic you want or your students needs.
I have also used kahoot. Students love the competitive nature of it and it is a great tool for reviewing information/content. I usually create student groups to help students collaborate and work together.