I personally wouldn't put too much thought into the oak. The last kit I did came with 2 oak chip bags which I added in Primary. I racked off of those and added a third bag which were cubes to secondary and the wine has been sitting on that oak for 6 months.
You are adding all 3 bags while fermentation is still underway and some of it is just to add tannin. The remainder is on the wine for such a short duration, I personally would just follow the instructions and question no further.
You are adding all 3 bags while fermentation is still underway and some of it is just to add tannin. The remainder is on the wine for such a short duration, I personally would just follow the instructions and question no further.