During the writing of a review paper it is very difficult task to add number of authors. However it varies person to person and their contribution in paper. but, there shld be any ideal number for adding the authors?
It depends on the reviewing article ares, in my opinion. If authorial team is making review on some topic that is ''full'' of information, than it is logical that there should be more authors.
it depends on how interdisciplinary the area is and how deep the review intends to delve in the various areas. for instance a review on pretreatment in bioethanol production and other bioconversion research, may include a physicist to review NMR, X-ray crystallography and other data available on the effects of various pretreatments on biomass pretreatment; a microbiologist to review the yeasts used etc; a biochemist/microbial physiologist to accurately review the metabolic processes; a chemical engineer to talk fermentation and process design and control; a chemist for separation and purification processes and someone to discuss lifecycle analysis. this is all hypothetical of course.
on the other hand, it can just be limited to one or two, if they are subject matter expoerts or if it is a well-reviewed area etc
It all depends on how detailed the (lead) author(s) want(s) the review out to be.
Mostly Journal allows 5-7, but it can fluctuate till 8 to 9. it also depends upon the author's contribution statement, which justified the typical role of every co-author.
There is no maximum, editorial in Nature commented on the apparent world-record breaking for the largest number of contributors to a single research paper: 5,154 authors!
Actually, at the very beginning of writing any text (on specifically controversial or open-end topics), no one could either dictate, limit or reckon the "maximum" number of papers to be included in a high quality review. But, some exceptions might be given herein, such as; the writer him- or herself, supervisor, editor and referees of journals, chapters or books, at least to some extent. However, it basically depends mostly upon the number of authors (from different disciplines) who collectively contribute to writing the review paper itself and scope (coverage) of the topic concerned how it is to be up-to-date or is to have potential for shedding "satisfactory" level of light upon future perspectives.
To my knowledge, the number of papers to be included within a review paper would not be limited, but rather it depends upon "inner requirements" of the topic of review to be written. I would rather say that, please "feel free" to include as much paper you would wish to as you can. Then, with the progress of writing and eventualy upon finishing, the text itself would say to you (thorugh realising it) that how many of the papers in number would be enough for the actual needs of the text being written. So, do not "bother" yourself; instead, you "just start" writing SIMPLY, that is ALL. By having more and more experince in writing along with the passege of time (surely demanding more and more somehow stressful reading, but presumably yiealding numerous 'published' papers at last) you will be fine. That's for sure...
3--5 subject matter expert authors are sufficient but no limit, I believe. The number of authors always depends on the research work means how interdisciplinary it is? adding more authors without their specific role in a research work/ review is unethical also.
I believe if research paper has someone's contribution then his name should be mentioned. Even a slight contribution makes sense. It would be wrong to limit number of authors. More authors cover broader aspects of the topic.
Depending on the topic and the content, I do believe that not more than 4 authors should be enough to provide a high-quality paper with equal contribution from each author.