After seeing gobs of AMCAS applications, please arrange most to least important to you and your application.
In reality, it doesn't matter...but imagine this scenario: you're reading dozens of applications and when you get to your 20th one, you have to hunt through a list of 15 for substantial things. It's a pain when the first three things are one-time things people did straight out of high-school that actually don't matter that much compared to the ICU shadowing experience you talk about a ton during your PS (just making up an example)...and we're hunting for substantial items...which end up being buried in the middle or at the end.
Just my opinion.
Caveat: Also it's been a year or two since I've helped out our admissions office, so AMCAS might be different now