Why it is advisable to apply L1 and L2 together?

[SurfUSA]

Hi

I'm going to apply for "US L1 Non Blanket Visa". Also, I want to take along my wife with me.

In few discussions, I found that it is advisable to apply L1 and L2 together in one shot.

Which is advisable of the following and why:
a) Apply for my visa and dependent visa together.
b) Apply for my visa first and then, on approval, apply for dependent visa.

Please let me know in terms of rejection rate and other complications for the above two cases.

Thanks in advance.