Choosing the length of savings certificates is an important decision. The issues of liquidity and the future direction of interest rates can make the decision difficult. Longer maturity certificates usually provide the highest return, but they also tie up your funds longer.
Shorter maturities provide flexibility to take advantage of rising rates, but usually lower returns.
Ideally, you would want the highest current return coupled with the ability to invest at higher rates if interest rates rose. Simply stated, with this strategy, you divide your funds into pieces and buy equal amounts of different maturity certificates. Each year, as a certificate matures, you would use the proceeds to buy a 5-year certificate. That way, as time went on, more and more of your funds would be earning the highest rate and you would still have annual liquidity. If rates rise, you have liquidity to buy higher yielding certificates.