You can get several years service from a battery pack if you care for it properly.

Don't cycle too often. More than once a month is useless. More than once at the begnning and end of the flying season is probably not going to be helpful. Just once a year is adequate.

Don't let a NiCd sit unused for more than a month. If you don't fly for a month, then you need to operate the radio for a few minutes, then charge overnight. That's all it takes to properly care for the batteries.

Average life expectancy of a NiCd pack is 4 years. Some people replace them at 2 years if they need it or not. (I don't) You can get 5 or more years out of one pack occasionally.

When a pack that is more than 4 years old goes bad, it often gives no warning. One charge it can be fine... the next you get 50 mah capacity out of a 700 mah pack. It was quite a suprize the first time that happened to me... luckilly it was durring the annual cycle-test of the pack. (The day before I had flown with the pack for 90 min with a .91 powered model.)