I agree with this. I've participated since 2016, but haven't yet completed all 25 puzzles, I usually burn out after about day 8-10 (partly due to the curve in difficulty).
I'm based in the UK, so the puzzles get unlocked at ~6AM which gives an hour or two before work if I wake up earlier than usual.
I think I'll still take part this year, but at a more relaxed pace.
This is correct. I am a PhD student and I know several undergraduates who get up at 5am (or stay up until 5am) to get started on the AoC problems ASAP.
I'm in central Europe and so puzzles unlock at 6 here. I've often thought that this time is nearly ideal for me. But at the same time, had I lived in the UK, it would have been absolute hell to try and be competitive. So an hour can make a huge difference.
I have had days where I've just caved in to the lack of sleep and decided to sleep in the next day, sliding on leaderboards in the process.
I'm based in the UK, so the puzzles get unlocked at ~6AM which gives an hour or two before work if I wake up earlier than usual.
I think I'll still take part this year, but at a more relaxed pace.