The third time someone calls to complain that the alkaline batteries they put in this leaked, they'll wish they used a soldered-in 3V lithium primary cell. Even though that goes against a certain ethos.
The lithium AA/AAA/CR batteries don't seem to leak. They're not widely available though. I use them for devices which mostly sit in a drawer and their lifetime can reach 5-6 years.
Tracking weather balloons. They use lithium AAs for power, and the mission only uses a fraction of their capacity. When the balloon pops and the payload lands, there's a good pair of AA's laying in some farmer's field, stuck in a tree, or otherwise sitting around waiting for you to clean 'em up.
Primary lithium batteries absolutely do leak, given enough time. Often the victim is an old Mac motherboard, search for "mac pram battery ruined motherboard" on an image search engine of your choice.
Haha, you just reminded me about replacing motherboard CR battery. Recently I was fixing over five years old computer, noticed the battery and thought "What does it do, I wonder if it works, perhaps I should replace it?".