I highly suggest in Miami if there is much of a line AFTER you recheck your bags to then exit and go back upstairs to the main entrances closer to the ticket counters where you have Precheck as well as Clear. Further tip is when you exit and get back upstairs there is a entrance right there but if you walk left when facing the counters (or that security entrance) the next one up has Clear and Precheck. It has saved us on a connector. I really seems strange when you are doing it the first time, but worth it as that line downstairs can really get long and move slow.