In some areas (e.g., high energy physics, big astronomy programs) there will often be hundreds of authors. Journals will sometimes list their institutions only on the online supplementary information (other than the ones that lead the study ... and these are noted). In practice, most academic societies have guidelines about this so it is important to be able to justify each author (some journals require you to say what each did ... this is useful for example if one person built some part of the apparatus but is not responsible for the results and the results get retracted). Places like the American Psych Association list who should and should not be an author, but I urge you to consult the main societies in your field (and of the journals that you publish).

Please let me know if the reference/site is of help to you:

The Winnower | The rising trend in authorship

https://www.thewinnower.com/papers/the-rising-trend-in-authorship

As shown in Figure 2, the average number of authors per paper has increased more than 5-fold over the last 100 years, going from ~1 author per paper in 1913 to ~5.4 authors per paper in 2013 (see Figure 3 for the shift in authorship distribution between 1953 and 2013).

Authors:Robert Aboukhalil

Affiliation:Mcgill University

Dennis

Dennis Mazur

In fact, there is no limitation, but you have to take care of the "rules of the game" in your country" In Croatia, up to three co-authors in social sciences are considered a maximum for full (100%) authorship of the paper. It is important for our career development, since we need to have a number of full authorship papers for academic promotion. In natural sciences, however, I know it is more due to the research process specifics.

don't worry about this issue, because there is no limit to the number of authors

It is based upon journals rules. 

No limit. Please see the links below.

https://www.nature.com/articles/nature.2015.17567

https://www.nature.com/articles/521263f

There are no limits, of course.

Personally, I avoid reading articles that have more than four authors, usually.