The usual workflow is to edge slide (shortcut: select the vertex and type GG. Type Enter when done.) one of the vertices along the circle until it reaches another one nearby and then to merge by distance to create just one node.
For example, your leftmost circled problem can be fixed by doing this twice. First edge slide the upper vertex in the circle to the one below it. Then slide the vertex that's in both circles to the one that's only in the middle circle. select all and merge by distance, and that's solved.
Unfortunately, this won't work in some case. Having done that, your middle circled area is still a triangle. Some people suggest subdividing the edge that is the circle part of the triangle. Other's suggest not bothering. It depends on how bad the triangle affects shading.
Sometimes you just can't fix the triangles without adding more geometry than necessary.