Select X, Y coordinates randomly but only do each pair 5 times

I have a code that selects an X, Y coordinate from a list of numbers, maintains it for 5 trials, and then moves to the next in sequential order (e.g. 3, 15 to -3, 15). I now want the code to randomly select a coordinate pair each trial but only test each location 5 times at the end of testing. Any suggestion for how I can do this?

X_vector        = [3; -3; -9; -15; -21; -15; -9; -3; 3; 3; -3; -9; -15; -21; -21; -15; -9; -3; 3; 3; -3; -9; -15; -21; -15; -9; -3; 3;];
Y_vector        = [15; 15; 15; 15; 9; 9; 9; 9; 9; 3; 3; 3; 3; 3; -3; -3; -3; -3; -3; -9; -9; -9; -9; -9; -15; -15; -15; -15;];

for k = 1 : numel(X_vector)
    for n = 1 : 5
        x = X_vector(k);
        y = Y_vector(k);
        % Now use x and y in some way.
    end
end

Answer 1

[Voss]

X_vector        = [3; -3; -9; -15; -21; -15; -9; -3; 3; 3; -3; -9; -15; -21; -21; -15; -9; -3; 3; 3; -3; -9; -15; -21; -15; -9; -3; 3;];
Y_vector        = [15; 15; 15; 15; 9; 9; 9; 9; 9; 3; 3; 3; 3; 3; -3; -3; -3; -3; -3; -9; -9; -9; -9; -9; -15; -15; -15; -15;];

n_trials = 5;
idx = repmat(1:numel(X_vector),1,n_trials);
idx = idx(randperm(numel(idx)))

idx = 1×140

20 23 12 19 2 18 16 22 3 1 14 2 1 16 8 18 22 22 17 7 11 20 26 4 21 19 4 6 13 12

for k = 1 : numel(idx)
    x = X_vector(idx(k));
    y = Y_vector(idx(k));
    % Now use x and y in some way.
end