The easiest way to do a heading change to get back on track is by looking at your track error (using the drift lines from start of track) and your closing angle (from end of track) and just add them together. the angles are done by eyeball, NOT messing about trying to do 1:60 rule and even an overworked brain should be able to see this and then add two fairly low numbers together. Trying to do it by proportions, which is the other way of doing it, works just as well,but you need much more spare brain capacity.