In Denver all our conventions run 4 hour slots (9-1, 2-6, 7-11).
Since PFS is PERHAPS one-third of the role-playing and maybe 15-20% of the total convention, getting them to change their schedule to fit 5-hour modules just isn't happening. All the boardgames, miniatures gamers, LFR players, local authors writing their own stuff and (especially) organizers and hotel staff are used to these slots.
Sure I'd like to take longer at a table and really role-play. In home games I do so. But writing longer convention scenarios because you think slots are too short in a standardized gaming world is like designing a 12-foot-wide car because you think roads are too narrow.
It just. doesn't. Fit.
PLEASE go back to writing modules that people can play in a 4-hour slot. Because most conventions aren't going to change their schedules and you're effectively locking yourselves out of that market.