Handmade puzzles, i.e., puzzles crafted intentionally by a real person almost never require guessing. However, a lot of “extreme” difficulty puzzles (or similar difficulty terms) in apps, newspapers, puzzle books, etc. are not handmade by a real person, but computer generated. There’s probably a logic chain that’s like 15 steps long that humans couldn’t reasonably follow, but a guess is likely faster and more enjoyable.

Someone else recommended Cracking the Cryptic on YouTube, which is a great source - the daily puzzles are nice because you can follow along in the video if you’re stuck, but they also have lots of apps with Sudokus that never require guessing. Another good source is Logic Masters Germany, which has lots of handmade Sudoku and other puzzles: https://logic-masters.de/

No.

I play several a day in an app for the last 10+ years and don’t recall ever guessing. I do sometimes need a hint but the hint is always one of the strategies someone else here linked that I overlooked.

Try to throw the puzzle into sudoku.coach’s solver and you’ll find a ton of techniques that completely eliminate the guesswork.

I find sukdokus extremely fun and I never need to guess on a 6/7 out of 10 in difficulty. My suggestion is to take it slow at lower difficulties to get acquainted with the simpler techniques before springing to the harder difficulties.

Check out https://youtube.com/@crackingthecryptic they solve like really hard sudokus without guessing and teach a lot of techniques on how to do it.

Try not to guess. It usually just leads to more trouble. Only really ok if you get out down to two numbers and can backtrack if your wrong.

Depends on the puzzle; it’s certainly possible to design Sudoku puzzles that necessitate guessing, but most do not. It’s possible you’re just not familiar with some of the more complex ways to make deductions.

Maybe check this list - it could be that your puzzle requires some of the more advanced techniques that you aren’t using.