It varies. I've probably written for hundreds of magazines over the past 11 years, about 150-160 articles a year at the peak, but that's fallen back recently because the pandemic killed some titles, while others stopped commissioning, and the whole industry has been nose diving for years. Which is why I'm on Medium. I had a regular slot with Military History Monthly in 2011, but they stopped running the stories - they were people's memories of WWII. Some of those can be repurposed in general interest titles though.