SSB - Confirming the prediction of SSB and should we only buy SSB at deadline day?

As mentioned at my previous post - SSB - PREDICTING FUTURE SSB INTEREST RATES , the OCT SSB will be lower to 2.70%.

The OCT SSB had been released at 1st Sep and the rate is 2.75%

That is 0.5% more than the prediction, why?

Looking at the Aug yield

You can see that 29th, 30th and 31st Aug end high around 3% yield. And if we calculate again

the average is 2.745% which round up to 2.75%. This matched the newly announced offer.

In conclusion, if you care about marginal percentage offered by SSB, you should only buy SSB as close to the deadline as possible.