There is no one-stop shop where you can search for your topic and find everything that is out there. Journals sell their contents only to select database companies - and while some journals shop around and have a deal with just about everyone out there, other titles are more selective. This means you need to look in several targeted places to make sure you are being thorough.
It is also a very good idea to use our databases/search
engines for other reasons.
In many instances searches in Google Scholar find you good search results, but you run into a paywall......
In other instances, you can find good search results, but none of the references in the paper you are looking over are hyperlinked, which means you need to figure out how to track the useful-looking ones down individually one-by-one.
We pay upwards of $500,000 every single academic year to provide you with linked, paid-for, full-text journal article access via our databases......the full list of which can be found below.