I think there would be only 2 cases in which 4 weeks of dedicated studying would not prepare you well enough for the DAT.
Case 1: You do not have a good science background. I'd say B's or higher in req science classes to be safe.
Case 2: You are someone who takes more time than normal to study. I think about a month's worth of studying is pretty typical? 4wk x 7d/wk x 6 h/d = 168 hours. If you get a review book that's 300 pages thick, that's half an hour per page. But if you know from experience you take longer to absorb material, increase h/d or wk.
I probably studied for about 30 hours the week before (super busy
) and that definitely wasn't enough time to learn the PAT portion and some anatomy/phys, but I was fresh off ochem and some nice bio classes, so I didn't feel the need to study those subjects as hard.
Briefly: depends on you. How much you already know/retain and how quickly you can absorb new stuff.
This is how I'd look at it. You will probably learn the most stuff fastest towards the beginning of your studies. Towards the end it's more confidence building/experience (which may or may not be of value). However, I think that it IS important to turn in your app early and have D-schools consider you in the first batch of applicants, which gets more and more important as time goes on.
SO: as time goes on, studying becomes less important (even if you're not as prepared for the DAT), while turning in your app becomes more important. I think you hit the sweet spot at 4 weeks.
Do it! Good luck.