def infer_time_unit(time_seconds_arr):
    """
    
    """
    if len(time_seconds_arr) == 0:
        return 'hours'
    max_time_seconds = max(time_seconds_arr)
    if max_time_seconds <= 60 * 2:
        return 'seconds'
    elif max_time_seconds <= 60 * 60 * 2:
        return 'minutes'
    elif max_time_seconds <= 24 * 60 * 60 * 2:
        return 'hours'
    else:
        return 'days'