Location based strategies

I have been thinking about local landing pages for awhile now. I have rolled them out to some sites successfully; others I have rolled out just don't budge. Just trying to understand the rhyme to the reason - and thought it would be good to ask BHW community.

For instance:

Core service is digital marketing - create core "digital marketing" page that targets nation wide.

Then, there are 5 core locations:

Digital marketing + Location A
Digital marketing + Location B
Digital marketing + Location C
Digital marketing + Location D
Digital marketing + Location E


All have their own unique content. I'm starting to see Location A rank for all OTHER locations too? Thinking this is just an indexing issue and could solve itself soon

Whats everyone thoughts on this strategy? If you think its a NO NO - be interested to hear WHY (being mindful that these pages have 100% unique content).

If you have done this before at scale - would be interested in hearing any tips and tricks that you've used to ensure that certain pages don't cannibalise others.

Over the past 5 years of studying the 1000's of expired domains- I have seen thousands of domain names expire for various niches. They were likely never sold to the local target audience and were speculatively registered for attempting to be sold to- those local city roofers for example: DallasRoofers, DallasRoofing, ArlingtonRoofers, TopekaRoofers, all dot com's of course, etc.

If you don't have backlinks and the serps are filled with the same answers.... it's a lot of work- but if your micro niche is really esoteric like "photogrammetry services dallas" probably would be easy- I don't use any Keyword finders anymore but well worth it. But to test use something like answer the public dot com with some specific cities say "birmingham alabama near me" and see what comes up in the trends for searches and then create content specific to frequent searched keywords to a specific city to see if it indexes.