I found today’s Killer extremely challenging for a “medium” puzzle. I finally solved it, but I think I probably spend an hour or more on it.

As I started it, I was a bit concerned but as I plugged along I saw something that popped it open for me.

I had paulv66's experience. It took me 55 minutes and more guessing than usual.

My opinion:
There are plenty of medium KSs I have struggled with.

With this particular puzzle, I completed a great deal of the bottom third and was stuck. I didnt relish the idea of filling in all the pencil marks.
As I did, I realized 9 could only be in a certain place. I think it was in column D
That is what I mean as "popped."
If I didnt see that, I would have been doing T & E. Once I saw that, the puzzle played out nicely.

I also struggle with medium KS puzzles from time to time. Difficult puzzles are meant to be challenging and can take me quite a while to solve. I find that I can solve the great majority of non KS medium puzzles in a few minutes and even the ones can cause me some difficulty never take more than 10 or 15 minutes to solve.

I’m somewhat obsessive about solving all the daily puzzles, although I will sometimes use the extra day or two allowed for the 12x12s and for Tuesday’s 9x9 and Friday’s KS. So far this year, I have only missed out on two puzzles. One was a difficult KS that I really struggled to get to grips with. The other was a medium KS that I worked on close to the deadline and eventually solved a few seconds after midnight CET, before the new daily puzzles had loaded, but received no points for.

Maybe it’s just the way I’m approaching these puzzles?

Should the difficulty of the medium Killer Sudoku be lowered a bit?

I don’t know how you program difficulty levels, but I find there can be a lot of variation. Today’s medium KS was about at the difficulty level I would expect. It’s just the occasional medium that strays into difficult territory.