If your CoG editor hasn’t recommended it to you, it might be best to forget about it. 
ICF turns off some of the guardrails that Dan Fabulich built into ChoiceScript for the sake of inexperienced programmers. With ICF enabled, you no longer need a *goto at the end of each *choice option – a guardrail that most writers these days seem to get around by using *fake_choice all the time, anyway – and you can use *if/*elseif/*else blocks without any *gotos.
It’s much-beloved of more experienced programmers, who tend to find the abundance of *goto/*label in standard CS infuriating – and if you intend to program outside of CS game writing, it’s probably worth it to learn the skill.
But having an explicit control flow – confirming to yourself and your reviewers where you intend to have the code go at choice and if/else points – can be helpful for novices (like most of us).