I've read about, and think I am observing, students spending time during quizzes looking up answers. Rather than a lock-down browser, why not just create a per question timer? I currently tell students they have to manage their own time, but in a classroom I project images and THEY ONLY STAY VISIBLE for a minute. This is the classic "practical" exam. Rather than students looking up answers on their phones or in text, they will need to stay alert.