Frankly, I don't see how much one stands to gain, or lose by doing so.

Using Affin as an example :
3 Months 2.48%
6 Months 2.73%
9 Months 2.75%
12 Months 3.05%

If one opts for even 6 months, you will get 2.73% pa, instead of 3.05%.

Now, if in 6 months time you renewal is due and OPR goes up, you again opt for 6 mths at, maybe 2.9% instead of maybe 12 mths 3.2% because there may be yet another hike in OPR. In that sense, you would never be able to opt for the maximum promo % percentage. At the end of it, 2.73% + 2.9%, your average 12 mths would be only about 2.81%, instead of one shot 3.05% based on Affin.

Don't make sense. For me, most of my funds are minimum 6-12 mths FD. I have smaller sums in shorter duration FD for just n case rainy days.