This is the entire numerical example from the above link, for those that are keen
Let's look at one such scenario for a member who has $700,000 in his OA, $250,000 in his SA and $63,000 in MediSave now. (Only standard interest rates are used here).
At his 55th birthday this year, $186,000 will be deducted from his SA, leaving him with $64,000. Despite this, he will still earn $17,500 interest from his OA, $2,560 from his SA and $2,520 from MediSave, giving him a total of $22,580.
If he shields his SA, he will have these balances and interest: OA $554,000 ($13,850 interest), SA $210,000 ($8,400) and MediSave $63,000 ($2,520), giving him a total of $24,770.
While shielding gives you $2,190 more initially, this is not sustainable, unless you don't withdraw any money from CPF for your own use, which is a ridiculous notion. So if your plan is to always spend the interest, over $20,000 a year, your balances in the SA will drop and cannot last beyond 10 to 15 years.
From then on, your options are left with either $700,000 or $554,000 in your OA (assuming MediSave balance and interest stay the same for this exercise).
If you have $700,000 in your OA, you can withdraw about $20,000 in interest annually for life without affecting your capital sum and about $16,000 for the lower sum. This means that if you do not shield your SA and instead choose to preserve your funds in the OA, you stand to gain in the long run, with more interest earned.