You've got 3 different schedules (Mo-Su, Mo-Fr+Sa+Su, and one for Mo-Tu-We-Th-Fr-Sa-Su). If you change one, but select another, the changes are saved, so what a lot of users do is set Mo-Su for one shift (e.g. night shifts), one for early shifts and one for regular days.
You then just toggle between them depending on which shift you have.
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