Texas UIM claim — insurance adjusters: when is a first-party UIM settlement actually final?

Hi everyone hoping to hear from insurance adjusters or claims professionals, especially those familiar with Texas UIM claims.

This is a first-party UIM claim with my own insurer, not a third-party liability settlement.

I’m still actively treating for accident-related injuries (spine injuries, injections, and a surgeon has recently recommended cervical surgery). Medical treatment is ongoing and additional records and bills are still being generated through workers’ comp.

From an insurance handling perspective, I’m trying to understand how finality works in Texas UIM claims:
1. In practice, is a UIM settlement considered final before a release is signed and payment is issued?
2. If numbers are discussed or even verbally agreed to, but no release is signed and treatment is ongoing, does the claim typically remain open to consider additional medical records?
3. Do Texas UIM carriers generally require a signed release to close the claim, or can a verbal agreement alone close it?
4. Is it common for UIM claims to be revisited when additional accident-related treatment occurs within the statute of limitations?

I’m not asking for legal advice — just looking for real-world claims handling insight from people who work these files day-to-day