That’s changed in recent years. Most people who make the Exercises today do it over the course of six to eight months while living their normal lives. These “Exercises in daily life” involve daily prayer and a weekly meeting with a spiritual director. These are called “19th annotation” retreats after a note (the nineteenth!) that Ignatius wrote in the preface to the Exercises.
If you are interested in this approach to the Exercises, I’d recommend reading The Ignatian Adventure by Kevin O’Brien, SJ, just published by Loyola Press. The book offers material for a 32-week experience of the Spiritual Exercises that Fr. O’Brien has used with both individuals and groups. The book is also full of short, pithy essays on many Ignatian topics.
You can see what the book is like by clicking the blue see inside button for the book on Loyola Press’s website.