I have created alerts in google scholar (one alert per researcher). The number of authors I can follow is limited (to 200) and thus I am not able to add more authors. Is it possible follow more authors? How?
Following multiple authors (or journals, or documents, or keywords) is in my view, much easier using a saved search rather than 'following' multiple different authors:
"A. A. Author 1" OR "B. B. Author 2" OR "C. C. Author 3"
and so on. That way, you can pack as many authors in as you like which avoids restrictions (but there will probably be a search string limit somewhere). Also, you won't receive two separate emails about the same paper if it contains two authors you follow. Reducing the number of alerts to one per category (authors, documents, sources) also cuts down on the emails you will receive.
Personally I use Scopus to do this. I have an author alert and also a journal alert. The reason I use Scopus is because authors and sources are assigned a unique ID which makes it more precise.
Simply edit the alert to add/remove authors/journals/documents when the need arises. I keep a list of the authors and sources that are currently inside the alerts, with their associated Scopus code, so I can easily swap out or add if I need to.
In Gmail (where my institutional email is redirected), I have labels set up for 'Author Alerts' or 'Journal Alerts' etc. Keeps everything tidy and separated from personal stuff.