Curious what the least crowded kiosks are in the 4 parks for picking up extra FP+s after the first 3 have been used. Assuming there is a difference, is there enough of a difference to make it worthwhile to cross the park to go to the “preferred” kiosk?
I had really good luck with the kiosk down by the entrance to the Jungle Cruise. I didn’t add extra FP very often, so I don’t have a lot of experience, but it seems to me that you shouldn’t bother waiting in line for a long time to add a FP. Trying a different kiosk location if the one nearest you is super busy sounds like a good strategy.
Only tried to make a FPP change in the parks once during 8 days in the parks. Found a reasonably short line and helpful CM near Stitch in Tomorrowland, no good choices (for us) at 4 p.m. on a day projected to be a level 2 but ended up at a 7.
In MK, we (like @SallyEppcot) had good luck with the kiosks by Jungle Cruise, and with the ones in the passageway from Frontierland to Adventureland. The line at the ones by Stitch was always long, but also always shorter than the posted wait of the attraction we got a FPP for.
In EP, we had good luck with the kiosks in the Innoventions breezeway near Test Track.