It’s not saying you can just roll a dice and pick a random highly skilled job every day.
View it as this person’s responsibility is to get food. So he can fish if he wants to or hunt or raise animals, farm, forage etc. Anything that brings food for the commune. (And like anyone can and should be a critic)
If he got tired of that he could change responsibilities entirely, depending on how labour is distributed in the commune. If he wants to be a lawyer he will have to study law, and if he wants to become a scientist he will have to study a scientific field too.