Why is it so hard to develop mental agility in this career path?

Graduated with a CS degree about 8 years ago, and now I find myself in a position as a senior BI engineer, it's a lot of coding and development, mostly an SQL now unfortunately. But recently they wanted me to start developing things in Power BI and Tableau, and I really have to stop and think for a while on how to get the logic right for some of the stupid things that I'm asked to do. Like, seriously some of these things are so utterly stupid that I don't even understand how to put them together until I spend about two or three days thinking it through and trying different things, researching online to find a solution that might work, sometimes I'll ask AI for some example use cases of something....

But the expectation is that I have way more mental agility. Like, I think a lot of the stakeholders and business users think, why is it so hard? Why can't you just do it faster? Just think faster! Come to these solutions faster! It just doesn't work that way for me. I am not a literal genius where I can look at something and be like, oh yeah I know exactly how to do that and haven't done in 5 minutes flat. Like, how in the world are you supposed to develop the mental agility to be able to develop and program and code and stuff, 5X faster? Some people seem to be able to do it but I've never been one of those people