How to include incremental research in the thesis I employ an incremental approach for my PhD research. In other words, at first, I propose a method to solve a problem and publish a paper about it. Then, I update my method by either improving its performance/optimality or adding more features so that it can handle more cases and I keep publishing papers reporting my progress. As a result, I have a pretty good publishing record, more than 5 papers as the first author in less than 3 years. However, between each paper, I sometimes make some major improvement such as completely replacing an old approach by a new (and better) one to solve the same problem.

At the moment, I am about to start writing up and face the problem of how to include all my papers in the thesis. My initial plan is to mainly focus on the last paper that I have published since it contains the best version of my research. However, doing so potentially makes my PhD research look weak since I have published many papers but only use one as the major theme of my thesis.

On the other hand, I am thinking about writing my thesis as a research diary that reports my journey to investigate how to solve one problem, e.g. at first I start with this approach, then after further research, I employ another one which results in better performance... But I am not sure if it is a right way to write my thesis.

My question is how to write a thesis for a incremental research. It would be great to hear from someone who was in the same situation. My field is computer science but answers from other fields are welcome.
From the point of view of the reader, jumping to the most sophisticated version of a method can be difficult.  A thesis isn't a textbook, but there are parallels.  A textbook often uses an incremental approach starting with almost a toy model to get the basic concepts sorted, before making it more realistic.  The assumed background knowledge of someone reading your thesis might let you skip the first step but not necessarily (don't write just for the examiners). It also allows you to indicate why you made certain decisions in the final version.