With water temps in the high 80's and a CYA of 70 I normally see FC of around 5.5 with a pump run time of 8 hours
Before a pool party I normally run the Aquarite for an additional 8 hour cycle to boost the FC to 6.5 or 7.
I run the pump, filter and SWCG the entire time there are guests in the pool.
After a large number of active guests are gone, I have seen levels as low as 3, but I simply run the Aquarite for an additional 8 hour cycle and by the next afternoon, the FC is back up to the target of 5. Within a couple of days, the water settles into it's normal FC of 5.5.
The type of party and the type of guests will have a greater impact sometimes than the number of guests.
I have noticed that with 6 or 8 adults lounging in the pool, a decrease in FC is rarely noted; however, with 6 or 8 active teens vigorously swimming, playing volleyball or basketball, diving, jumping, and generally having a good time that the FC can decrease by 2 or 3 ppm within a few hours.
Your mileage may vary
PSG