I often find alkaline batteries in clocks and remotes that are years past the expiration date still going strong. Haven't had one leak yet. I use mostly duracell but I don't think it matters much.

Totally drained alkalines will probably leak within months of being drained. Healthy alkalines with a good charge will most likely not leak for many, many years. Don't store them inside your flashlight for a long time and you should be fine. The consequences of any leak will then be very minor.

This thread prompted me to do a battery check. Open each item and remove or rotate the batteries for examination.

5 flashlights scattered around the house: all fine.

Flashlight in bag and 3 in car: all fine.

5 remote controls: Ah, HA! One battery has suspicious stickyness along the seam. Replaced both.

Wall clock: no problem.

Beard Trimmer: well, carp. I obviously hadn't thought of this one. Haven't used it in a couple of months, battery leaked all over the inside. Half an hour with a pencil eraser and some fine sandpaper got it working again, but I'm going to have to replace it.


Moral: ANYTHING that doesn't plug into the wall needs to be checked.

I go on a set schedule. Buy a bulk pack every spring/fall and put those in all my gear. Then what was in the gear goes in the toy supply. That way my batteries are never more than 6 months old.
Some devices with electronic power switches will drain batteries left in them and can drain them too far and help cause leaks, but anything with a mechanical power off I've not had any leak problems.