There is no such limit. In a systematic review, you are supposed to find ALL studies that meet the study eligibility criteria for your research question.

For example, we are currently evaluating 5173 search hits in a systematic review. Several thousand is not unusual. The review of search hits is initially done using titles and abstracts. The studies that make it through that phase are then reviewed using full text.

This same question was asked 5 years ago. If you introduce "

Google scholar for systematic reviews: what limit on search returns?" in google you will find this question and numerous answers in researchgate.

You can also check this manuscripts (both of them open access)

Variation in number of hits for complex searches in Google Scholar PMID: 27076802

Optimal database combinations for literature searches in systematic reviews: a prospective exploratory study PMID: 29208034

They will help you.

Good luck!

Gordon L Warren and Manuel Vélez-Díaz-Pallarés, thank you for your help.

Search results in Google Scholar depend on the country where you enter the search string and other data from your Google account. Therefore, this might not be the best data base for such queries. Maybe have a look at Durach et al. (2017):

Article A New Paradigm for Systematic Literature Reviews in Supply C...

Hi! If you are interested in learning about specific capabilities/limitations of Google Scholar, you can read my recent publication: Article Which Academic Search Systems are Suitable for Systematic Re...

I hope this helps!