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Both of these are correct and will work, but they come with slightly different options when defining the day or date on which issues are published. See the documentation on Days of publication for more information on this. As a general rule, it is usually Because eventually a day of publication will need to be specified for each of the “issues per cycle” it is usually simpler to define publication cycles with smaller issues per cycle which in turn means it is less work if you pick the more granular time unit when you have multiple options - so in this case using Month as the Cycle length Time unit (with 1 issue per cycle) likely to be the simplest approach, even though using Year (with 4 issues per cycle) will also work.