Fairly easy Medium :

I I dont test, I just see a pattern that leads to a contradictio. There are many named pattern that eliminate a cnhoive and they are not considered as a guess, such as XY wing and the UR rule. In this case there cannot be a 6 and 9 in box 4 col3 because that would place both a 3 and a 6 in rhe same cell in row 4. You can see that more easily with greens, but I use the iPad and have to remember possible options for cells. That has the advantage that it becomes easier to mentally trace the consequences of a choice. That technique is sometimes called Nishu I think

Anyway, my vision is very poor, only 16 percent in one eye, thats why I use the iPad and make many typing errors.

It seems that there are differing opinions as to what the Nishio technique actually is. No matter. What I am trying to understand is the difference between testing, which you consider to be guessing, and other techniques which you consider valid. I accept that pattern recognition is very different from testing, but what about coloring. If one color illustrates the consequences of making one choice and another color illustrates the consequences of making the other choice, is that any different from testing whether the first choice creates a contradiction.

My sympathies for your failing eyesight. My vision is also becoming poorer but from a different cause, glaucoma. When I started having difficulties reading my computer screen I went in a different direction from you by stepping up to a larger, higher definition screen. I like my setup because I am still using the same keyboard.