Another option can be
% this will work for integer times
times = [1 2 3 4 6 7 10 12 14 15 17 19 20 21 29 30 32 34 36 37 40 41 42 43 44 45 49 50];
one_sec_int = min(times):max(times);
is_update = ismember(one_sec,times);
checking_interval = 10;
num_updates_interval = movsum(is_update,[0 (checking_interval-1)]);
%M = movsum(A,[kb kf]) computes the sum with a window of length kb+kf+1 that includes the element in the current position, kb elements backward, and kf elements forward.
[max_n_updates,idx] = max(num_updates_interval);
first_time_when_max_update = one_sec_int(idx);
