Depends on batteries you use and what voltage, current, etc.
Usually you want to go as high of a voltage as you can while maintaining a useable voltage for controller, motor, dc-dc and charger. For motorcycles, 72V, 96V are good voltages to work with. Series parallel is quite common for smaller Ah batteries. I've got 160 Headway 38120S 3.2V cells (10Ah). The pack I've designed is 32s5p, so ~96V and 50Ah. You always want to parallel batteries first (put 5 in parallel) and then put groups of those 5 in series, 32 times.
You cannot have BOTH series and parallel at the same time. You do one before the other, otherwise you create short circuits.
Parallel creates a higher Ah "group". Put those groups in series for more voltage. But you can't, for instance take 6 12V 50Ah batteries and put them in series to get 72V, and then parallel them to get 300Ah. You do one or the other for each cell.
Hope it makes sense. If not, could you draw a schematic of what you mean?