[pineapple888]

OK n00bs, there are five main reasons to make corrections to ICM:

1.) skill edge
2.) fold equity in the sense that other donks bust each other out
3.) fold equity in the sense that you might get better situations later
4.) uncertainty in assigning ranges
5.) asymmetrical ranges (where a slight misjudgement in ranges has a much greater downside than upside)

Part of the skill of STTs is understanding how important each of those five factors become in various situations, to set your minimum edge correctly. This min edge can range from quite large to potentially slightly negative (on very tough tables where the sizable blinds are about to hit you).