Open mat at E4 BJJ is the perfect time to come in and work on the Jiu-Jitsu lessons that you learned in class over the week. 

Most people us this time to drill or get some live rolling time in (sparring/grappling). 

Open mat is not a structured Jiu-Jitsu class like the other classes, rather it’s an “open gym” time where you can come in get some extra training in with your teammates.