I guess it's true based on my experience on my various girlfriends (because I also have the "magic finger")
I've been reading many thesis, doctorate journal, men's magazine that have real sexology talking about various techniques, and so on, as long as it's from a legit source (not including myth, "they say" article, or just a story from any strangers that claim something that hasn't been proved scientifically). but the most common techniques is you must rub gently but fast (don't scratch it!!!) on the g-spot area and on the end of the vagina wall (I couldn't find any good pictures on the internet to describe it).
if you know the techniques, it's very easy to make a woman squirt. but not every woman easy to do it, some you just have to try it hard, but in the end I always can make them squirt. and based on my experience, women prefer squirting when men's penis are inside the vagina, they say it's more sexy and intimate that way. so after I finger them, they give me the cue when they are gonna squirt, and that's when I should penetrate.
in this kind of internet era, it's should be easy finding techniques that can make a woman squirt. you just have to google it a bit, there are a lot of web that talks about it.
good luck finding and practicing it!!!
PS: no! squirting isn't only in Japan, but also in American and European porn and maybe other country as well, but it's not common there for women to squirt because there's still debate in the western part of the world if squirting is really squirting or just a piss (you can read it in wikipedia about "female ejaculation", I'm surprised that it's very well described about the debate). one performer that often have a squirting scene in the U.S. that I remember are Sativa Rose, Flower Tucci, Sophie Dee, Annette Schwartz, Ava Rose, Jenna Presley, and Jada Fire, and many more (see? there are a lot of western performer that often have a squirting scene)