Yes, you will still create powerful foundation for swimming by learning a plethora of new skills and expanding on what you know. It always depends on what level you start with and for absolute beginners doing only 5 days is a great start and I still recommend doing 8 days for best results. Advanced beginners and intermediate swimmers will get more out of 5 days than absolute beginners and our focus is on impeccable water safety, deepening your skills and improving your strokes dramatically, so the longer the better, but if all you have is 5 days, then of course, you will still improve. For ideal circumstances, I always recommend 8 days- 3 weeks.