I will support this, perhaps, unpopular opinion. Whenever I read I-751 instructions and interpret them literally, I come to that conclusion:
- "Submit copies of documents indicating that the marriage upon which you were granted status was entered in good faith and was not for the purpose of circumventing immigration laws. Submit copies of as many documents as you can to establish this fact, to demonstrate the circumstances of the relationship from the date of the marriage to the present date;"
This is supported by a few lawyers I asked this question (including the one I worked with), and by Jim Hacking (YouTube guy) too.
It's always immigrant's burden to prove they're eligible for a benefit.
I'm not advocating sending local bus schedules to USCIS. Only relevant information supporting bonafide marriage in whatever volume it takes: if it's 1000 pages, let it be 1000 pages. In a nicely organized packet, officer can easily find whatever they're interested in. In my personal experience, there's no way IO will read every letter in a bank statement. Unless there's something specific they're looking for, they'll get a few samples from here and there and make a decision. Solid packet will be a good indicator the applicant takes immigration laws and rules seriously. It will also highlight the effort that went into collecting ans organizing evidence.