ive always done this, i cant say whether it helps with leveling or not but it does ensure you have enough of the rare ore to make the better wheel and pickaxe + the wear on the wheel, which is the more expensive one, is greatly decreased.
I always try to only be collecting two kinds of ores at a time. The new smelting option is letting me feel a little better keeping the rarest ores around since I only need four to make a bar then.
I like to have the cart open in a free window when my wolf is mining, that way I can multitask on another daily and drop a few ores in between tasks. Makes for a pretty steady workflow