Incidentally, "venting the cans at intervals" would have no affect on reducing pressure other then momentarily - the fuel will quickly regain equilibrium pressure (which is based upon a liquid's vapour pressure and temperature) once re-sealed.
Which might be fine if the container is completely full. But if there is an airspace in the container, being not completely full (because you filled it to the nominal capacity as marked) then there is quite a lot of airspace, which is going to build pressure with altitude increase.
I won't say that I have never done it, but I sure do it as little as possible, and with caution, at low altitude!