I have dozens of zigbee contact sensors, ranging from 8 years to brand new. All of my old contact sensors last up to 2.5 years, but every new zigbee sensor needs new batteries within 6 months.
I have many repeaters and a robust zigbee network. I can move the old sensors anywhere and they work correctly and maintain excellent battery life.
Many new sensors require 2 AAA batteries (instead of the button batteries), yet they still need replacement within 6 months. They are all manufactured by well-known brand names. It's a PITA to keep up with replacements.
Why are new zigbee sensors so bad at managing battery life?
Start by listing the brand and models of the ones that have the longer life and another list of the ones that you are having the shorter battery life with.
My general advise is to contact the brands of the ones with the shorter life to see if they may have a firmware fix for that device to help better manage the way they wake up to send the data to your network.
Anything more would be to invest in battery eliminator cables for the ones where you have a power socket available near that you can take advantage of so you only have to worry about the life of the actual product itself at that point.
Here is the list of my zigbee contact sensors that I currently use. The absolute worst sensors are in the garbage, so I don't have that list.
I cannot provide a list of good battery life "old" zigbee contact sensors. I used them for my dad's house since they need to be reliable. I remember one sensor is a NYCE hinge door sensor that's been reliable and good battery life.
Here is the "bad battery life, but good enough to continue using" list:
