I found the opposite to be true, in my case.
After completing 2 3+4 subjects in year 11 (methods and hebrew), I firmly knew that Hebrew (scaled 41.5, raw 28

) would be relegated to my bottom 2, to join my enhancement subject, University Mathematics. This left my other year 11 score (44 raw in methods, scaled 47.5), to round out my top 3 along with Specialist Mathematics and Chemistry. This prediction worked marvellously, with Chemistry (scaled 46.5), and Specialist Maths (scaled 51.7) filling the rest. These were scores which I felt I was going to achieve (around abouts) pretty much all year.
The point is, if you know your abilities, there's no reason why you shouldn't pursue predicting your top 3, so long as you actually are a good read of what you can achieve. Remember that the bottom two only contributes 10% of the scaled scores, meaning pouring in the extra effort to get 40+ may not be worth it as 30-35 will only net you a decrease of 1. Compared with if you put those hours of effort into a top 4 subject, for which the difference between 30-35 and 40+ is marked and worth it. However, if you're in doubt, then you would definitely be safer in having a fall back and working just as hard in a 4th. It all depends on you, and good luck with it
