Many date fields

Hi AndreaRoth 

Assuming that the period of activity is from rental start to end date, try the following measure:

Count by Time Period =
VAR StartDate =
    MIN ( Dates[Date] )
VAR EndDate =
    MAX ( Dates[Date] )
RETURN
    COUNTROWS (
        FILTER (
            'Fact',
            'Fact'[rental_date_begin] <= EndDate
                && 'Fact'[rental_date_end] >= StartDate
        )
    )

Note: You will need a disconnected dates table.

Please see the attached pbix.