Sanding Glider Wing

I'm in the sanding phase of finishing my sailplane wings and I have a
question about the technique for sanding the wing. I'm using a 44"
sanding bar wtih 320 grit, using wet-sanding technique. My question
is when sanding at a 45 degree angle to the chord line, are you
supposed to keep the sanding bar perpendicular to the chord line (in
other words, translating the bar along the 45 degree line) or do you/
can you rotate the bar to be closer to perpendicular to the direction
in which you are sanding?

Up until now I've been maintaining the bar perpendicular and I am
coming up with areas where the sander has not reached, yet at the high
areas I am almost down to the last bit of primer. I know this likely
means I have some low areas to build up, but I happened to rotate the
sanding bar about 15 degrees or so, towards the 45 line, and the low
areas began to disappear. Am I fooling myself as to a true surface,
or have I been needlessly stringent on my sanding technique?