I don't understand how the multiple landmarks works. If you just max all of the landmark distances wouldn't some landmark near the starting point eventually dominate as you move away from it? Once you get halfway through the path the useful landmarks would be returning lower and lower values while ones behind you return larger and larger values. Or just in general one far-away landmark would complete nullify any input from useful ones.

It seems to me that you would need a step to select useful landmarks but the code doesn't seem to do this and I don't see it discussed.