It would not make sense I don’t think Clear’s Reservation Lane would make sense for those who have PreCheck, for the most part. I have never waited in the PreCheck line at MCO more than a few minutes, over the past 7 or 8 years. Unless, of course, you happen to be one of those unlucky individuals who has PreCheck missing from their boarding pass, due to TSA’s random security action.
There are a limited number of time slots available, each day, If you don’t find a suitable time before your travel day, you can also stop at the Clear kiosk on your travel day, and inquire if there are any open times before your flight.