The "through" here eliminates any doubt that Wednesday is also a working day. It makes it explicitly inclusive. In AmE, we might also say "Saturday to Wednesday" in this situation.

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"Teaching in ... typically entails working Saturday through Wednesday."
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According to Cambridge Dictionaries Online, through preposition - US from one time until another time: The store is open Monday through Friday.
Question: What might the equivalent in British version be?
The "through" here eliminates any doubt that Wednesday is also a working day. It makes it explicitly inclusive. In AmE, we might also say "Saturday to Wednesday" in this situation.
I work (from) Saturday to Wednesday.
I work every day except Thursdays and Fridays.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.
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