Mine has been doing the same (also Mazda), but I don't recall it being that bad in the past; I'm kinda suspicious about the quality of the 'Panasonic' batteries I've bought from Ali Express the past year or two.

What adds to this suspicion is all our Tiles seem to have been going through batteries quite fast; I replaced the batteries in two car fobs and four Tiles last week - this time I've added a little piece of paper on top of the battery with the date on it so I can actually track their lifespan!

Main FOB (frequent use) about a year or so, secondary (less frequent use) 2 - 3 years.

I put some of mitre10s house brand batteries in my tiles last time and they lasted longer than the energizers that I also got from either mitre10 or bunnings.

It seems that tiles are negativly affected by interference, as the ones that sit at home all the time have shorter life than the ones I carry with me.

I am 3 years, daily use as i am in a call out business from commercial property to property.  Not issues yet (Colorado Ute)

Kookoo:

My Mazda key fob seems to run out of battery about every 5-6 months. Is that normal?

I replaced mine in October and over the weekend I got an advisory warning that the battery was low, but it didn't appear again after that. 

I'm inclined to think it was a spurious warning as the car doesn't get used much so the battery should last much longer than 8 months. 

With my wife's car (Leaf) the first sign of the battery dying was I couldn't use the entry button on the car itself to lock/unlock, but could still do so by pressing the button on the fob; and then (as with my own car) the only way to start the car was to hold the fob directly near the start button. Getting the message 'no key detected' even when the key was less than 30cm away from the start button was the sign that finally got my A into G to replace the battery...

2-3 years on my  Honda.  I replace the battery when it starts to be un-responsive from a distance (50 feet)

Around 14 hours...as my key fob is my aged iPhone X

Old Corolla is probably a couple of years. Modern Nissan about the same. I get good brand lithium button batteries from ebay, ten are usually cheaper there than one in NZ. I keep them up in a top cupboard because very bad for kids if they get them.