I have no knowledge about LSAs.
But I have an experimental.
My FSDO has been quite helpful and easy to work with.
My yearly program letter calls out about 15 locations where I am planning to practice for proficiency or participate in racing.
Historically my planning never works out.
In the past I never made it anywhere close to all those 15 different locations in 1 year. I am not aware of any limit in the number of locations you can state in the program letter.
Anyway, my 15 locations cover all of the routes we usually fly.
Nearly all of California, Nevada, Utah.
And if I want to go to a location that I did not plan for at the moment of issuance of the program letter, I only need to send an email to my FSDO, stating the new location(s) as amendment.