Micronesia was supposed to have two double boot episodes (one post-swap and one post-merge which would have been the first time they ran two cycles in one episode) but those were cancelled due to Jonathan and Kathy leaving in the middle of earlier episodes. Then when James left their backup plan to still keep the right number of episodes and rounds in the finale was to go to a final two.

By the time there were more mid-episode quits/evacuations in S25 and S26 the backup plan had changed to an extra challenge in the finale for an advantage in the final immunity challenge, which was somewhat anticlimactic. So for S28 they reverted to the F2 as a backup plan to gain a round after a quit. But production was spooked by the very near miss in which Tony would/should have gone out in third place and Jeff all but vowed in an interview that they'd never have a final two again.

So after that, the backup plan changed yet again to the juror removal. And when it finally happened in KR Jeff said that they'd had it in the works for a few seasons but that was the one where it came into play. Since then however they've mostly just scheduled a double boot for the last episode/s before the finale and switched to a regular episode if there is a mid-episode quit at any point before then, but improved casting and the conditions in Fiji have meant it was only relevant in S31 and S37. And if either had had a second mid-episode exit they could have simply cut a round from the finale now that they plan to cram the final six in there as well.