Gift cards needs to be fully spent in one transaction?

Hello,

It depends on the generator you want to use.
The "coupon" generator will create HikaShop coupons, so it is something that you can just one time.
The "points" generator will allow the customer to gain points ; via the "user points payment" plugin, that customer could use its points to have discounts (and use them as he want, in several orders if he has enough points)

Regards,