Hold on, be careful, with 12 magnets and 12 coils you are going to have single phase.
I think you have missed something somewhere.
Let's consider a simpler case of 8 magnet 6 coil. Normally this would be connected with opposite coils in series so that you have 3 phase groups and these are star connected to make it 3 phase. The electrical displacement between the 3 sets of windings is 120 deg electrical, although to confuse things the mechanical displacement is 60deg but we needn't go into that.
Now we could split this winding into 2 sections each using 3 coils. If we make a star point of the starts of the first 3 coils and do likewise for the second 3 coils we now have two 3 phase windings which in the perfect world we could connect in parallel to get half the voltage of the original winding and 1/4 the resistance.
This is still 3 phase but it is parallel 3 phase.
Now leave the first 3 coils the same but for the second set we make a star point of the finishes. We now have two 3 phase windings, but at the instant when one phase of the first winding is maximum positive, the equivalent in the second is maximum negative because we have reversed the coils.
We can still rectify the two windings separately to dc and the effect is the same as for the earlier case, but we can no longer directly connect the two windings in parallel on the ac side as these windings are reversed in phase relative to one another.
If now in the final case we connect the star points we have 6 phase. The 3 leads of the first winding give us normal 3 phase with an angle of 120 deg. The second 3 likewise but these are 180 deg shifted from the first, resulting in a winding with 6 leads with a separation of 60deg electrical. This is 6 phase and at cut in the rectifier sees 2 coils with a displacement of 180 deg and the cut in is the same as phase volts x 2. In the 3 phase case the voltage is the vector of 2 coils at 120 deg or 1.73 x phase volts.
The 6 phase case therefore gives a lower cut in speed for the same turns. At high loads the rectifier conduction pattern changes and the thing behaves much as the 3 phase case. The overall efficiency is a bit lower as the peak currents per winding are higher but the effect is small. Overall the more sloping speed characteristic of the 6 phase may offset this loss in improved prop matching but the effect is not great. 5 phase falls between the two with a factor of 1.9 x phase volts.
Now with 12 magnets you have a messy situation for 6 phase as you have 9 coils in a single layer winding so each of the 6 phases would be 1.5 coils, messy and more trouble than it is worth.
16 magnet is ok with 2 coils per phase. Overlapped windings with 18 or 36 coils is ok for 12 magnet but a difficult winding with the space available.
I hope you have followed this. With the same number of magnets as coils the coils are all in phase (or 180 out) so it is effectively single phase with all the problems that go with it.