Question: why are periods critical in peoples lifes?

Duncan McNicholl answered on 8 Nov 2017:

I’m not sure what you mean by periods.
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If you mean periods of time, like “this is a critical period in your life”, people often think that the times when they made decisions were really important, like when they decided which subjects to do at school, or which university to go to or whatever. My experience so far has shown me that opportunities generally come round again, so I don’t think decisions are worth worrying about all that much, especially if you try your best with what you’ve got.
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If you mean periods in the school day, that’s how we split up your time between the different things you need to learn, and without them you’d have to decide all that for yourselves, and then check with your teachers when they were free, and it would all get very messy very quickly.
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If you mean menstrual periods, that’s how you have babies. Babies are pretty critical, and also extremely cute. Did I mention that my brother had a baby in September?