Ultimately, the TSA Agent decides who they take next. Most times when using the Clear Lane w/ PreCheck, I am immediately the next person in line with TSA (after other Clear's in front of me). However, there have been a few times when the agent has decided to take other PreCheck/Non-Clear before me (up to 3). Usually not a big deal unless I have a tight connection and I ran outside to smoke (the real reason I have Clear and Pre/GE). In a PreCheck heavy airport, Clear can make all the difference!