I just picked a term that I know for sure I have never searched on my phone or work PC and started typing. I know for a fact that Google Instant is turned on on my work PC. I started typing the work Feudalism (my daughter has a project on this, that is why it came to mind) after feu on the PC, I had an entire list of Feudalism search suggestions and a page full of potential links. I tried the same thing on my phone and got the same results. I really don't know that in my case it speeds things up tremendously, but it does help you find the correct search term to find what you are looking for.
Just my $0.02 worth,
BigRedGonzo