I understand the way double-slit is shown and ridges pattern calculated (e.g. https://personal.math.ubc.ca/~cass/courses/m309-03a/m309-projects/fun/Slits.html#topic1) is by assuming two identical waves coming out of the slits. But wave length of visible light is about 1/1000 of slits separation distance.
I recall reading photon is huge in volume even for small wave length, only that wave density is tiny at large distances from "center" so it can go to two slits, no problem. But does it go in a symmetrical way? Or in fact two waves from slits are not same in "intensity" (if such way of thinking even makes sense for photon), but by averaging out many photon the pattern is still the same as if each photon were doing through two slits in a symmetrical way? TIA