Murphy's law says it will fail at the most critical moment, just when needed most. My Casio watch battery ran out when I was deep in the woods. Fortunately the first battery lasted 5 years. And I am sure the new generations of these products have user-serviceable batteries. If you get one, make sure you carry an extra battery.
Most collectors start out carrying their tools in a bucket.
This usually works well until the day they have to hike up a long trail. Or the day they hit it big and must carry out 60 pounds of rock, plus the tools they brought with them. Then they say never again and buy a rucksack, the small backpacks used by students for carrying their books to school. This also works adequately until they have a similar trip and must carry a lot of weight. Either the rucksack straps will break or even worse, they don't break and they must bear the entire weight on their shoulders.