Daily leave is the basic type of leave. It works exactly in the same manner, as in previous versions. This type of leave spans across multiple days. It is possible to select only full (non-partial) days for leave. Users are always able to select this type of leave.
The below image presents a situation, where Jira administrator adding new vacation type, can see that "Type of vacation request period" (1) always contains daily ones:
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And when choosing any of the above presented, one can spot always "Daily" feature to be present in "Period type" option(1):
%20-%20They%20are%20always%20possible%20to%20be%20selected.png?version=1&modificationDate=1536229751152&cacheVersion=1&api=v2)