Well, if you put the RM3000 into semi flexi, you save RM10.50 interest. For full flexi, you are offset the monthly RM10 charges + you save RM0.50 interest.

you mean you don't have at least 3k in the bank account on a day to day basis?

For semi flexi, once you put in the 3k, you can't take out easily, but this 3k I'm talking about is when you get your pay... let's say 10k... and by month end you will still have around 3k for savings... and that's accumulative before you dump in to your semi-flexi to save your interest but I have already saved the interest since day 1. 

And should I need to use this 3k, I do not need to go over the counter and wait few days and pay service charge to get it e.g. booking fees for a new condo... immediately without thinking, I can just write out the cheque without knowing whether I have enough balance in my normal acc after I transfer to my semi or not coz I definitely know I have my savings all there to touch anytime.

Another example - while waiting for my reno guy to complete the job, all my savings is in my full flexi account, it took him 3 months to complete the job and that 3 months I saved quite a few k on interest before I fully settle his bills.

Installment amount will be same throughout the whole period regardless how many u put in the current account.

Your 200k is just use to offset the interest, not use to pay principle yet. So you still own the bank same amount of money by right even u put extra in current account.