Changing batteries

What is the current thinking on how often should batteries be changed out of a flashlight?

Are there certain batteries that will be more prone to leaking? I had a problem with a few MiniMags last year when AA batteries leaked and got stuck. I couldn't get them out and just tossed them. Since I'm just getting into some higher end lights, I don't want them destroyed by leaking batteries.

Thanks ahead

When in doubt use lithium batteries. They pretty much can't leak and if they do it is non corrosive so it won't hurt anything. Plus they usually have a 10 year shelf life. I centered my light collection around CR123s with the exception of the ITP A3 EOS I wear around my neck.

I have no need to go rechargeable atleast not yet. I don't bun through batteries too quickly.

A few ground rules:

-Never use alkalines, especially in high output/high current drain lights. For one, their performance is absolutely atrocious, and they are very prone to leaking under high drains.
-Use Lithium in lights that are going to be put away for a while. Not only are lithium primaries a much better performing chemistry than most rechargeables and especially alkaline, in extreme conditions, they usually have a much larger capacity, so you get longer runtimes.
-If you get into rechargeables: Ni-MH perform very well, much better than alkaline, and are better in the long run. They also won't leak and ruin the light. They're stable. Lithium Ion's, on the other hand, require some careful maintenance and "supervision" while in use. Be sure to read up on the dangers of mis-using li-ions in the batteries section.

Moving to the Batteries section...