Finding the right pieces for the LEGO sets I'm putting together from my random mixed piles of bricks has a certain limits of how easy it is to find the correct pieces. I just need to find a good balance between the speed and the effort.
The thing is the sorting, how granular I want to go. I could sort every single type and variant of pieces on their own, even by colour. But then it would be a lot of effort to find the correct container for the right piece. Not to mention the amount of containers to hold all those different kind of bricks.
I've found it better and more efficient to keep similar pieces together. It's a bit more challenging to find the correct kind of brick among them, but there is usually different variants of similar pieces used in many sets anyway so I can search them at the same time.
Finding the correct piece among all those similar ones is harder for the first sets collected from the lot as there are more pieces to go through. But at the same time it's easier to find at least the more common pieces that are used in many sets. It becomes harder later on when there aren't that many pieces left. The opposite is true for more rare pieces, when I need to find a single piece that is only used for one set it becomes easier to find once there are fever pieces left overall.