Water has amazing power to wear things out. You can see that just from the way riverbeds are hollowed out of solid rock, just over the passage of years. This means that you should be careful with your home. While you might think that a little bit of water falling somewhere won’t hurt anything, you could end up paying for that assumption with roof repairs and water damage.
When you have different levels to your roof with gutters, it might seem like it should be ok for water to just fall down naturally to the bottom gutter, but that isn’t something that is recommended. Instead, there should be a downspout that sends the water out, not on the roof below, but straight into the gutter at the bottom of the roof.
Of course, this makes for a more complicated installation, but it will cost you a lot less than the repairs which would result from not doing it correctly.