How common is for good and high quality research papers to contain 1 or 2 paragraphs of copy paste from previous papers of the same researcher?
Is this common or it's a red flag of low quality research?
Edit: 2 papers from the same researcher tackle different problems. To solve each of these problems some sub methods are used. On paper A sub methods 1, 2 and 3 are used. On paper B sub methods 3, 4 and 5 are used.
Sub method 3 is copy pasted (exact same explanation) on both papers A and B. The newer paper (B) makes no reference to paper A. The papers have nothing in common, aside from using this sub method.