Is 15 sections too many for a journal article? I am planning to write a journal article about real-world algorithms solving a practical problem for an IEEE Computer Society transactions journal. The section outline currently is as follows:


Introduction
Related work
Problem definition
Simple algorithm for a simpler problem that cannot be scaled up to the real problem but is very interesting from mathematical viewpoint
Several mathematical observations from the simple algorithm
Simple algorithm that can be scaled up
Good, slow algorithm, as used in literature
Implementation details of our version of the good, slow algorithm
Another good algorithm from the literature and some improvements to it
Even more improved version of the Section 9 algorithm
How to deploy Section 6 algorithm for worldwide use
How to deploy Section 9/10 algorithm for worldwide use
Results and discussion
Discussion about one important point that could be claimed to invalidate the results but in reality doesn't
Conclusions


So, there are 15 sections. In IEEE double column style, the text is now 7 pages + references + biographies, but I expect it to grow to 10 pages + references + biographies because some of the sections are empty currently, their text not being written yet.

Now, my question is: do I have too many sections? I have intentionally kept the sections concise, not being too wordy. So they explain things just once and expect the reader to understand. So, the paper is not overly long.

The paper is quite conclusive because it explores 4 different algorithms and manages to optimize one of them to be fast enough to be used in practice. I don't want to remove any content because it would make the paper less conclusive. The results are important as well: the best algorithm as optimized by me runs over 60 000 times faster than equivalent prior art algorithm in the Section 3 problem.

I don't see any simple yet good reorganization into subsections: for example, Section 5 really has to be immediately after Section 4 so that the reader doesn't forget the important things from Section 4 when reading Section 5. So I can't combine Sections 4-10 into subsections of an algorithm section, because in the middle there would be a mathematical observation section unrelated to algorithms. In theory, Sections 11-12 could be combined to be subsections of a deployment section, but that would save just one section number. Another way to save one section number would be to do this:


Results and discussion


13.1. Results
13.2. Discussion
13.3. Discussion about one important point that could be claimed to invalidate the results but in reality doesn't



After really hard work, I came up with the following barely acceptable outline having less sections:


Introduction
Related work
Problem definition
Simple algorithm for a simpler problem that cannot be scaled up to the real problem but is very interesting from mathematical viewpoint
Several mathematical observations from the simple algorithm
Scalable algorithms


6.1. Simple algorithm that can be scaled up
6.2. Good, slow algorithm, as used in literature
6.3. Implementation details of our version of the good, slow algorithm
6.4. Another good algorithm from the literature and some improvements to it
6.5. Even more improved version of the Section 6.4 algorithm

Deployment


7.1. How to deploy Section 6.1 algorithm for worldwide use
7.2. How to deploy Section 6.4/6.5 algorithm for worldwide use

Results and discussion


8.1. Results
8.2. Discussion
8.3. Discussion about one important point that could be claimed to invalidate the results but in reality doesn't

Conclusions


Is this 9 section outline better?
Yes, you improved it a lot with the 9-section outline, because:


It is much easier to communicate the tiered the structure of the paper to the reader, which makes readers and reviewers much happier.


It is easier for readers to scan through and understand the main outline of the paper, instead of having to figure out for themselves which points are more closely related.
It is easier for your to preview the shorter outline in words near the beginning, than if you're thinking of it as 15 sections.

It may slightly save you space, because subheadings likely take up less room than main headings.


Here are two additional potential revisions to further streamline:


Change point 5 into a subpoint under point 4. It's still about that simple algorithm. (As I just saw, lighthouse keeper also advises this.)
Shorten the title for 8.3. (Obviously, you're giving a generic version, but it could be done briefly by saying "Addressing Entropy Concern," replacing "Entropy" with a reference to whatever issue thoughtful reviewers may anticipate as a problem.)


Someone in your field may have better comments about whether the information you want to pack in here is all too much to effectively demonstrate in a 10-page paper. In particular, the simple, unscalable, mathematically interesting algorithm might not be as related to the rest, if you must cut something.