Which is better completing CPT in 4 mothns or compleing it in 8 months?

[shujaath]

Respected sir,

I am currently on F1 and want to know which option is better, completing CPT in 4 months or completing it in 8 months?

So far I have seen people opting for 4 month CPT only.

Could you please help me in knowing the advantages and drawbaks of obataing CPT for longer or shorter period.

Thanks.