Fan,
Your scheme won't work, because the servo isn't fast enough to respond to the signal driving it at the rates you are attempting. The scheme would work if you put more delays in

Certainly most RC servos have bandwidths of maybe 4 - 5 hertz maximum, so they'll move 180 degrees say in 0.25 secs. That means your code will really have to wait for the servo to move anywhere before it can make a judgement to stop where it is.

And you can't run at clock/4

Steve