I usually buy the ones for a certain area if I have not been to it previously.Once I know the area, I seldom use them again.
I don't rely on Googel Earth etc to much, as things change. If I am interested in an area, I go there to check it out prior to hunting it.
Back when you could order from USGS for 50 cents a map I had large collection of New Mexico. I gave them away when I left there.Now a t$10 apop,I am a little more selective.