Lessons :
1) Do not apply for sta-21 core option if you are below e5
2) Do not apply if you cannot max out on pre-board score
3) If you cannot apply for core probably not worth the time it takes
4) Sta-21 is skewed for older "sailors"
3 and 4 not completely true, I was picked first time up as a core and only 24! So if you think you got what it takes go for it!