❔ How to avoid multiple loop of collection?

static public Intervals SplitIntervals( List<WorktimeScheduleInterval> intervals )
    {
        var workdayIntervals = intervals
            .Where( interval => interval.IntervalType != ShiftIntervalType.Break
                    && interval.IntervalType != ShiftIntervalType.EmptyType )
            .SelectMany( interval => new[]
                {
                    interval.TimeShift,
                    interval.TimeShift + interval.Duration
                } )
            .OrderBy( ts => ts )
            .Zip( intervals
                .Where( interval => interval.IntervalType != ShiftIntervalType.Break
                    && interval.IntervalType != ShiftIntervalType.EmptyType )
                .SelectMany( interval => new[]
                    {
                        interval.TimeShift,
                        interval.TimeShift + interval.Duration
                    } )
                .OrderBy( ts => ts )
                .Skip( 1 ),
                ( start, end ) => (
                    Start: start,
                    End: end) );

        var breakIntervals = intervals
            .Where( interval => interval.IntervalType == ShiftIntervalType.Break )
            .Select( interval => (
                Start: interval.TimeShift,
                End: interval.TimeShift + interval.Duration) );

        var emptyIntervals = intervals
            .Where( interval => interval.IntervalType == ShiftIntervalType.EmptyType )
            .Select( interval => (
                Start: TimeSpan.FromDays( 0 ),
                End: TimeSpan.FromDays( 0 )) );

        return new Intervals(
            workdayIntervals,
            breakIntervals,
            emptyIntervals );
    }