Hi there!
If this were my client, I'd be having a very serious and educational chat about the direction the campaign is headed and strip it back to basics. The below suggestions assume the site doesn't currently rank anywhere that's going to bring them any real volume of traffic.
Remove the Subdomains Subdomains are treated as separate websites so sanfrancisco.website.com is viewed as a completely different website to seattle.website.com. While that may be ok for the end user, what this means for optimisation is 2 different link building campaigns, two sets of content (both of which need to be unique and still genuinely valuable) and 2 sets of ranking signals.
You mentioned they have 14 locations set out like this so what you've actually got is 14x the work needed. Honestly, this is not a good use of your time or their budget.
Remove the Spammy Blog Posts The reality is, nobody is likely to actually read a series of blog posts that are so blatantly keyword heavy. The most probable outcome is that users will be given a very low quality vibe and steer clear of the brand in the future.
Also, having that much keyword spam on your site is playing with fire. It doesn't provide a good user experience and search engines these days are easily capable of understanding exactly the aim.
Blog Posts Don't Target Keywords
Blog posts should absolutely have a target audience and perhaps a common search phrase in mind, but they shouldn't really have a keyword focus like other pages on your site - there should never be a post that's built around the phrase Insurance San Francisco for example.
Focus Your Time; Work on the Primary Domain
As I touched on above, splitting your time across 14 subdomains is not a great use of your time or their budget at all. Rather than trying to churn out 60 low quality blog posts from questionable sources to meet this arbitrary requirement, spend that same time writing 1 or 2 high quality, uniquely valuable posts each week then promoting them through various channels like social media, influencer outreach etc. It's going to give you far better quality signals than huge amounts of rubbish across 14 subdomains.
More importantly, this approach gives users a reason to stay on your site and build that crucial rapport. in the insurance industry, people tend to shop around and do their research for a bit before they commit to the purchase and swamping them in keyword spam is not a way to build that relationship.
Go Back to Basics
From my experience, any site that's in this bad shape is probably going to have a lot of other fundamental issues (thin, keyword heavy content, a terrible backlink profile, poorly structured and keyword heavy navigation etc) that really should be addressed before even thinking about blog posts.
If this were my client I'd be treating it like a brand new website and going from the top. Ignore the domains and plan to take them offline, plan the site architecture and nav then get to work on improving the site one element at a time with a heavy focus on the user experience and the real end goal (traffic that converts) rather than keywords and SERP position.
You can rank #1 all day long but if your site is heavily spammy, it isn't going to convert!
That's probably not what you wanted to hear and perhaps not the sort of info that you're looking for here but to be honest, I think any further time that gets tipped into forging ahead with those spammy subdomains is time very poorly spent. I hope you find it helpful either way!
It may be that the client is very reluctant to such a drastic change so it would take a very strong educational approach and, if they're financially driven, focus on the fact that optimising a single site, they need to pay you to do less work for more return; "more for less".