Senior developer here, it is challenging. It's designed to be. I'm to the point now though that im a bit burnt out on it. I miss a weekend and then don't have a desire to catch up.
I used to do like 20 days or so in uni, but now I just wish it was in any other month but December - it's just impossible to find the time with all the year-end tasks and ceremonies.
I’ve thought the same in past years but for last year’s aoc I didn’t try to finish all the puzzles in December and let myself work on them whenever I had time throughout the year. It’s a bit less fun because the general zeitgeist isn’t focused on it outside of December but still totally possible to finish them at your own pace.