calculate time difference in an event list

So it's super unwieldy, and I figure there must be a better soltion out there, but here's the measure I came up with that displays results in HH:MM:ss format. If you put it in a table with EMP.BADGE.ID, you get a total duration any exit entries within the sliced timeframe. Hopefully this gives you a workable starting point.

Time Onsite = 
VAR Duration = CALCULATE(
    SUMX(
        ADDCOLUMNS(
            VALUES(Table2[Event Local Time]), 
            "Duration", DATEDIFF(
                CALCULATE(
                    MAX(Table2[Event Local Time]), 
                    FILTER(ALLEXCEPT(Table2, Table2[EMP.BADGE.ID]), Table2[Event Local Time]<EARLIER(Table2[Event Local Time]) && Table2[Readers.Reader Function]="Entry")
                ), 
                Table2[Event Local Time], SECOND)
        ), 
        [Duration]
    ), 
    Table2[Readers.Reader Function]="Exit")
RETURN
IF( //Convert from seconds to HH:MM:SS
    Duration<>BLANK(),
    INT(Duration / 3600) & ":" & 
        RIGHT("0" & INT((Duration-INT(Duration/3600)*3600) / 60), 2) & ":" &
        RIGHT("0" & MOD(Duration, 60),2) 
)