when interest rates are falling, i would put in 1year FD, instead of 1 month FD.
when interest rates are rising, i would put in 1 month FD instead of 1 year FD.
similarly for mortgages, rates will rise. i would put in a 3M,6M or even 12M sor/sibor rate, not 1M.
you need to see the average difference between 3M, 6M, and 12M.
this you must ask AMK or whoever with access to 1M, 3M, 6M, 12M SOR/SIBOR.
for example if 3M and 12M difference is 0.2%, I would use 12M rate because i expect interest rate to increase around 1% per year.