from typing import Counter


def sum_all_dates(counters):
    """Sum up all the counters for each court across all dates.
    
    :param counters: A dict of name-counter pairs.
    :return: A counter object with counts for every court across all dates.
    """
    by_court = Counter()
    for court, counter in counters.items():
        by_court.update({court: sum(v for v in counter.values())})
    return by_court