Hi Jonny, thanks!
With a longer "cooking time" the Count could pass around almost freely, without worrying too much about the Sun. After some playtesting, it was found that the correct time is 0.45 seconds. The slower time is just too forgiving (the game is LBYL, not EAFP :-), the faster time will lead to accidental deaths during correct moves. The time shall not allow the player to pass a fully illuminated "voxel" to the opposite side.
The shadow falls at 45 degrees and is orthogonal, so you can count the level "voxels" to find if the goal will be lit, to pass the level without dying. But dying a few times to learn the map is a valid tactic, although more frustrating :)