Study on series – parallel led
There are couple of connection way for led, series and parallel respectively.
First analyses were series on led circuit ..

Advantage: Design is simply, according to led work theory All LED have the same work current . in here the work current of led equal to input current. And not , concerned about Vf, base on the scale of led power input, as long as large scale short do not occur , the led circuit would guarantee that working order. There was a litter drop in led luminous .

Disadvantage: whole led circuit is brake when a led trigger short.
the input work voltage is biggest that parallel circuit.

The follower we are talk about parallel

Advantage: the input voltage was small. Production process is simply. Without affect other led worked when a led is short.

Disadvantage: the Vf of Led have strict requirement (consistency), inconsistency of led Vf can lead current is inconsistency . in case some led current would quickly increase ,then temperature increase, All of this would be made Light decay.