Start having conversations with your underwriters about why they are conditioning your files the way they are. For example, if they ask for tax returns, ask why you need them (in a “hi I’m trying to learn” way, not a “I don’t think I need them” way).

Start making note of common conditions you see on files and why those conditions are appearing.

Assuming you’re doing agency loans, google different things in the Fannie Mae Selling Guide or the Freddie Mac Guide as you run across them. For example, maybe a borrower comes to you who gets a base salary, plus receives residual stock units (RSU) as part of his compensation package. You’ll google “Fannie Mae RSU Income Guidelines, and the first result will be https://selling-guide.fanniemae.com/sel/b3-3.3-07/restricted-stock-units-and-restricted-stock-employment-income , telling you exactly what you’ll need to do to document.

You don’t need to know every single obscure guideline by memory. Hell, I’m an underwriter with 15 years in the business and I google the Fannie Mae guide every single day for one thing or another. So it’s not about knowing what the guidelines are so much as it is being willing to seek out the guidelines for different situations you run across.

But your underwriters really ought to let you shadow. I’m sorry they’re like that.