[quote=@Webmaster]
<Snipped quote by Disdain>

I see some of the first and fewer of the second. There are some that complement each other's strengths at the cost of shared weaknesses.
[/quote]

-Spectre- Usually, the two need to coincide for the sake of scheduling. It's fairly unwieldy to be an S-Class team that doesn't share time, finances, and everything because the pay for an S-Class mission doesn't get any better for doing it as a team.
-People on their own have weaknesses too, so the situation you say is usually fine.