I used the default settings for years, which means ctrl+click picks colors from the entire merged image. Recently I switched the default behavior to color pick only from the layer I’m on (and alternate action is pick from merged image.)
This has immediately improved my work speed, can’t believe I hadn’t thought of it before. If you’re the type of artist to use many layers (I have 2 multiply layers, 1 color, 1 hard light, and extras depending on project…) then this change is a must. I used to right click > isolate layer whenever I wanted to pick a color on a multiply layer, now I just sample it directly. Also, if I want to change a base color below the multiply layers now, I can just go to the flat color layer and color pick freely without worrying about isolating the layer or picking multiplied colors.
It’s so much better I don’t even know why default behavior is like that anymore!
I think it just really depends on the workflow you have. You use many adjustment layers, so picking a color from a current layer is preferred. Many people might not use them as much, maybe only at the end, and might need it for stuff like: mix in a color from the background into the character they’re painting that’s on a different layer. The default behaviour is also less confusing for newcommers, since it clearly picks the color they see on the canvas.
Better advice in my opinion is to use ctl+alt+click instead when you want to sample from the current layer instead of making a change you might not remember anymore in two weeks and then get confused about the behavior.
For me I most of the time want to sample the color I see the other 20% of the time I just add the ALT key to the keys I press.