I'm not OP, but if you are a reasonably high-earning professional common on this site, you trigger a ton of stuff. I used to take about that long to do mine, although I've gotten much faster. In a normal year, I typically file forms 1040, Schedule A, Schedule B, Schedule D, Schedule 2, 6251, 8606, 8949, 8959, 8960, 8995 + state versions of some of those. I'm also married, so I calculate all permutations of joint/separate with itemized/non-itemized, which also requires you to actually figure your taxes instead of leaving it blank and letting the IRS do it.

It gets really complicated very quickly, but if you are single, have less income, and it's only from wages, it's much simpler.