An open or closed condition won’t drive battery usage, unless of course it’s constantly being opened/closed, but that’s not your situation. Does that sensor report temperature? If so, perhaps that could be contributing to battery usage, especially if the temps fluctuates a lot. How old is the battery?
I typically see a couple years from my Iris zigbee sensors (CR2 batteries), and just about a year for a few of my Ecolink zigbee sensors (coin batteries). Those Ecolink sensors report temperature A LOT because I have them outside, which tends to drain them quicker than most of my Iris sensors. I also have a Gen 1 ST multipurpose sensor from way back that uses 2 AAAA batteries, and it’s on my mailbox. That thing is going on year 3 with the last battery change and it’s only at 25% as of today.