How did you become a financial modeling whiz? Getting lost in details and adjustments

I'm trying to hone my modeling skills by going through case studies, but I can never fully complete a model perfectly by myself and it is extremely frustrating. I know the general basics and steps to do, and I end up with a largely fleshed out model for the most part. But if the prompt throws out something new or complicates the situation (ie. build an lbo model where company decides to ipo the company during holding period and offload some equity or accounting item Im not familiar with / company has granular line items that doesnt fall into normal line items on BS), i am at a complete loss and need to look at the answers. Otherwise, if its a straightforward templated modeling problem i can do it just fine, but i know that things are not as neat in the real world.

Coming from a liberal arts background, is it b/c of my lack of understanding in how line items flow together and general basic accounting principles that is hurting me? How does anyone memorize all the FASB rules? Any advice for me? I think in general, I have formatting and readability down pretty good as well as making my calculations easy to follow and laying out the model in a presentable manner.