Unless there was a change in the last few years, the way it always worked was quick release after initial publication, glued. Printed after some time has passed, sewn. So latest event OHCs are usually glued, (and with cheaper paper), and creator runs that come in volumes or long ago crossover collections are usually sewn. Makes sense that X Of Swords was glued, unfortunately.
Has something to do with which country they’re printed in. Whichever does sewn takes longer to import, so they can’t get the event books on shelves before the post-conclusion hype dies down too much.