I also think it depends a lot on whether you still have MCU1 or if you upgraded to MCU2. I ungraded my 2016 AP1 MS90D to years ago, Dec 2021. Prior to the upgrade, I was only getting a software update about every 3 months. However, after I updated to MCU2, the update frequency was back to about every 3-4 weeks on average. That’s continued even to now, with have received update about 2 weeks ago.
No idea what the MCU1 update frequency is now versus the roughly every 3 months I was seeing two years ago, but wouldn’t expect it to be any more often then roughly quarterl