Spring and Fall is when I clean all the windows really well. The sills, panes and screens are all washed. The window frame is washed. I hate some of the creepy dead bugs, but I push through. All the screens are taken down and sprayed with a hose, washed with soap and water, sprayed again and go back up in the Spring. I am always amazed how much dirt is actually on them. Does that mean that dirt is taking up some of my viewing room? In the fall I actually store them as I am always amazed by how much more I can see outside when screens are not on the windows at all.
So clean the windows. It makes the house so much brighter.