Kyle S

SEO Manager
SEO Manager, co-owner of Press Synergy
Do you mean doing gmb posts? What we'll do is everything we do a blog post, we'll throw a snippet of it on the GMB as a post and entice users to click through. Also doing posts about goings on in the community, any charity work the company has done, etc.
I don't think it'll hurt you at all, but it won't really help either. I wouldn't waste my time on them unless you had extra budget to spend and wanted to make something impressive looking for a client.
By themselves they probably don't do a lot. We use them as part of a google stack.
I don't make many of them, but what I do is create and download a radius map on freemaptools.com, then upload that to a Google my map.

Then I create a 500 word article on article forge and spin it with spinrewriter.

Then I manually place the pins and add in the spun content, links, and additional keywords.

If I'm feeling really ambitious I'll stack a few of them together.
Not sure if it's an algorithm update. Could just be click data being funky because of the holidays. How are they looking compared to this time last year?
What a lot of people are missing here too is engagement signals. CTR, directions, etc. At a certain point there's only so much you can do. If people don't interact with your listing you're going to be dropped from the map pack.

On top of that, where are you trying to rank? There's only a certain radius Google will show your GMB in most niches. You can temporarily get a bump with things like press releases, geo specific pages, but then the CTR has to be there as well.

Also, how much spam is there? If your competition has keywords in their title and you don't, you're at a disadvantage (although I'm seeing evidence of Google cracking down a bit on this now, including some of my test GMBs)