FL - the navigation technique you refer to is known as the 'Standard Closing Angle' technique. It is actually a refinement of the 1 in 60 rule, as I will try to explain:
If you realise that you are A miles off track and wish to fly B miles back on to track, then you need to turn towards track through angle C whose sine is equal to A/B. For simplicity, however, C=(A/B)x60. Now consider that we normally prefer to fly with reference to time rather than distance when considering regaining track and let's say that the time T taken to regain track (in minutes) is flown at V miles per minute, so that B=VxT. Then we can simplify the track correction equation to C=(60/v)x(A/T).
Now for the clever bit. Let's choose A to be numerically the same as T, that is we fly for the same NUMBER of minutes back towards track as we were miles off track. Then A/T=1, and hence all we need to do is turn through a Standard Closing Angle C equal to 60/V, where V is our TAS in miles per minute. Thus for something like a Bulldog doing 120 knots the SCA is 30 deg, but for a PA28 at 90 knots, it's 40 deg. The larger the SCA, the more significant the time error because we're only flying at an equivalent along track speed of VCosC. Fortunately for those using this technique at 90 knots, cos40 is 0.766 which is near enough to 3/4, so what would have taken 3 minutes will now take 4, i.e. 1/3 longer. To summarise the Standard Closing Angle technique:
1. Turn towards track by your SCA
2. Hold the new heading for the same number of minutes as you were miles off track.
3. Turn back onto your original heading and then check that the DI is correctly synchronised with the magnetic compass and that the aircraft is accurately balanced.
4. Adjust your ETA.
This technique works a treat - it doesn't need hard sums as I've just done those for you!! All you have to be able to do is to estimate distance off track and be able to add or subtract the SCA - if you like you could always work it out for each leg before you get airborne!!