To a point you can't get too heavy an arrow IMO but there is no stead fast rule except that in order to stay within warranty your arrows must weigh 5 grains per pound of draw weight.
For hunting purposes a heavy arrow is more desirable with few exceptions.
*A bow firing a heavy arrow is quieter which is less likely to cause a deer to "jump the string".
*A bow is more efficient at launching a heavy arrow so the heavy arrow starts out with more Ke and momentum than a light arrow and it maintains its speed over distance better than a light arrow. This all equals better penetration from the heavier arrow.
*A bow firing a heavy arrow is less likely to have a failure due to more of the bows stored energy being transferred to the arrow instead of being absorbed by the limbs and riser.
*A heavy arrow is less effected by crosswind (all other things being equal)
For example.......
Arrow A weighs 350 grains and leaves the bow at 300 fps. It will loose 22 fps and 10 foot pounds of Ke over 70 yards.
Arrow B weighs 500 grains and leaves the same bow at 260 fps. It will loose only 13 fps and only 7 foot pounds of KE over 70 yards.