Insurer keeps requesting more documentation every time I respond - is this a stall tactic?

I filed a homeowners claim back in September after a pipe burst in my basement. The damage is real - we have a contractor estimate for $27,000 and about $6,000 in personal property losses. I submitted everything the adjuster asked for: contractor estimates, photos, receipts for the damaged items, even a plumber's report explaining what caused the burst.

They came back and asked for 3 more years of maintenance records. I found what I could and sent it in. Then they asked for documentation that the pipe had been inspected in the last 5 years. Then they asked for receipts showing i replaced the water heater. Now they're asking for a statement from a "certified plumber" about the pipe age and condition before the loss - which makes no sense because the pipe already burst.

It's been 4 months. Every time I send something in they go quiet for 3 weeks and then come back asking for something new. Is this normal? Is there a point where they legally have to make a decision? I'm starting to think they're just hoping i'll give up or run out of documents to send.