With the plethora of databases comes a variety of different interfaces.
Some databases might use be accessed using different interfaces.
Some interfaces can access more than one database.
Most people are creatures of habit: they find a database they like (usually an important one in their field) and get used to it. When they have to search another database (or if the database has been bought out by another company), they can often find the different interface confusing. As a result they sometimes simply don’t conduct the search.
I like to assure people that searching in an unfamiliar interface is like driving someone else’s car. When you’re in your own car, you know where everything is, and as soon as you get in, you’re on your way. However, when you drive someone else’s car, you haven’t forgotten how to drive, but it takes a while to figure out where everything is (I always find the placement and use of window wipers baffling) and to adjust before you can get going.
In the same way, using an unfamiliar interface can take a little while to get used to. But it’s worth spending 5 minutes playing with it before you start your search. I often find a quick look at the help or advance search can orient me in a new interface. Sometimes I will do a dummy search to see what the results list looks like and how I can refine and alter the listing. Just like with cars, some databases have more bells and whistles than others. Nevertheless, if simplest model car can get you to your destination, the most barebones database interface cab get you to the information you want.
I would suggest familiarizing yourself with EbscoHost and ProQuest interfaces. Both of these interface can access multiple databases and even search them at the same time. I would also suggest becoming familiar with the two cited reference databases I mentioned before: Scopus and Web of Knowledge.