Is mindfulness for quick enlightenment being exaggerated in the Sutta MN10?

I was reading about mindfulness here . At the end I found this paragraph > Let alone seven years, anyone who develops these four kinds of > mindfulness meditation in this way for six years … five years … four > years … three years … two years … one year … seven months … six months > … five months … four months … three months … two months … one month … > a fortnight … **Let alone a fortnight, anyone who develops these four > kinds of mindfulness meditation in this way for seven days can expect > one of two results: enlightenment in the present life, or if there’s > something left over, non-return.** Here Tathagata saying one keeping that kind of mindfulness for 7 days can get enlightenment? Is it exaggeration, translation problem or understanding problem or it's true?