Does 'improfile' keep a constant number of samples between successive segments?

I'm trying to extract several profiles along a path in an image. If I loop the function between successive coordinate pairs, I get the correct result.

Example:

for k=1:N
   profiles(k,:)=improfile(im, xs(k,:), ys(k,:), samples, 'bilinear');
end

But 'improfile' should be able to do this without a loop, as it handles a path with successive points. But when I try this:

   allprofiles=improfile(im, xs, ys, size(xs, 1)*samples, 'bilinear');
   profiles=reshape(allprofiles, samples, []).';

I get a different result and it seems like the number of points interpolated in each segments is not consistent. Is this the way the function is supposed to work, or am I doing something wrong?