In course walks it is important to have a plan - especially if you go early in the order. I find it really helps to bounce ideas off of someone you trust on the ground for another perspective. I walk a track accordingly, and if there are line options or turns I walk both. It really helps me to visualize, and therefore I benefit from walking the whole track from the perspective that I will be seeing it on course (around the turns not just the lines). I plan my approach to jump one through the finish timers. I make note of the time allowed, and develop a plan depending on the horse I am riding and the goal for the day (am I schooling to improve my horse's confidence? Am I going for the win in a speed class? Am I trying to jump a safe clear before a jump off?) If there is a jump off, I walk this track as well to find the most efficient track.
It is critical to walk the course with the specific horse's strengths in mind. For example, if my horse has a very small stride but is handy around turns and I want to win a speed class, I probably won't take the leave out in a line but I might be able to make up time around a turn that another rider could not complete.
As long as it is possible, it is best to walk the course at least twice. In a grand prix or a nations cup, I walk it more than twice!