No DFC, I think it's you who is missing the point. The whole point of the SCA is that it's quick and easy to use. You seem to be transforming it into your next thesis. Navigation can be made simple and pilots like me like simple. The way the RAF teach navigation is that you should be on track as much as possible and if you are off track, you should either fly to a feature on track you can see, of if you can't see one - use the SCA.
But to try and explain how the SCA should really work, look at the following diagrams, for which I didn't use a computer as I'm not that clever - I used a Tucano nav plotter which is set for a speed of 240knots. These diagrams are drawn as accurately as I could - which is probably more accurate than I can fly!
In the left hand diagram, the pilot sets off on a track of 360. He has chosen a good check point at 4 minutes, a mast with good vertical profile which he thinks he will be able to see and he can fly to if he's off track. However, he's made the mistake of believing the met man when he said there was no wind, when there's actually a wind of 270 at 60. Getting clost to his mast, he can't see it because it's into sun, so he can't use the ''fly to a feature'' technique. At 4 minutes he sees it to the left at what he estimates is a range of 4 miles. His brain goes into action and he realises that
a) he must get back on track and....
b) he's got to do something about maintaining track when back on.
He activates the SCA part of his brain which has already been programmed that flying at 240 knots, 240 divided by 60 equals 4 miles a minute, 60 divided by 4 is 15 and therefore 15 degrees is his SCA. (He doesn't have to do the maths in the air, he already knows the SCA for his speed). So, he decides to change his heading 15 degrees for 4 minutes, (one minute on the heading for as many miles you are off track) and he will fly this heading of 345 until the stopwatch gets to 8 minutes.
Now he's turned, he wonders what sent him off track. Was it a cumulative error or was it a once only error? He noticed he was drifting quite a lot, so he decided it's cumulative caused by believing the met man. He does a quick calculation and work out that after 16 miles he was 4 miles off track, and that equates to about 15 degrees of error. So he makes a decision that he will change his heading to 330 until 8 minutes and at 8 minutes he will fly heading 345. He flys this accurately and as you can see, he is almost on track. Not exactly on track, but will certainly be able to see his waypoint at 10 minutes.
In the right hand diagram, the pilot encounters weather at 2 minutes. He's flown to the right of track, but he doesnt know how far until he sees the mast to his left at what he estimates to be about four miles. The SCA training kicks in and he applies a heading of 345 which he will hold until 8 minutes. He then decides whether it's a cumulative or a once only error. he knows he got off track avoiding weather, therefore it's a once only error, so there is no additional correction to add.
It's not perfect, but it's the best there is in the circumstances. Errors include the fact that the trigonmetry of the SCA based on the 1 in 60 rule isn't exact, the groundspeed may not exactly be divisble by 60, the distance off track can only be estimated and that there is usually a short delay while mental gymnastics take place - for example, the pilot in case A above will have spent a bit of time on the heading of 345 before deciding he should really be on 330. But, the point is that the pilot will end up close enough to track to identify and fly to his next turning point.
SCA sounds complex at first, but the beauty is that it's quick and easy to use once you have had a bit of practice at it - and it doesn't require a visual feature on track to fly to.
As I said, I've used it all my career while flying visual navigation and it works well in practice.