How Often Do Insurers Change Their RX Guides and how Important is the "RX Fill Within" Section?

1. Just wondering how many dramatic RX guide alterations your typical FE insurer will have and how often?
2. When writing an application, how crucial is the RX Fill Within section of the RX guide? I assume underwriters are very strict with this?
3. What happens if the fill date isn't available?
4. What happens if a medication isn't present in a particular insurers RX guide? Does that mean they don't care about it and will approve the app? Or is it more "murky" than that?

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