Dumb question.... I understand that cruise altitude should be above 300ft. AGL, even +500 going west and odd +500 going east.
If I am planning a flight along rolling terrain, or flying say from flat land up over hilly, mountainous terrain where the ground elevation rises 500-1000ft. or more ASL, do I constantly need to ensure my cruise altitude is adjusted? Whats the easiest way to do this? Can I use the elevation off a map, and use time/distance calcs along my route to know when to adjust? Or is it less precise than that, and just pick a few prominent landmarks on my route and know to be at correct AGL at those?