Many of the most important decisions we make in our lives are like that - we don't know where the ball is going to end up and we don't have lots of practice so don't get much feedback. All sorts of important decisions that we usually make only once or twice, such as what university to go to, who to marry, what career to go into, where to live, are those that we cannot really practice. We can make a choice and then sometimes find out it is the wrong choice - we can certainly get feedback on that - but we never get feedback on the alternative choices that we did not make.
I'm thinking that probably we should encourage more experimentation at school, so that students can explore more options and come to know themselves better. I've been involved in an R&D team that has been investigating internships recently and one of the positive things that could come out of such an experience is that students have a better idea of whether this profession or industry is really a good career choice for them or not. If it is, hopefully it helps them in narrowing down their choice of subjects to study for their IB diploma and then later at university. If not, then there is still time to explore other options or simply make a choice to study a broader range of subjects in order to keep their options open.