Ah, now, sitting with work colleagues on a LH flight is a different matter.
In the past I've agreed with work colleagues we'll choose whatever seat we want (or can at the time) and if we sit together/near each other then fine, but not something I'd seek out to do.
Especially in CW sitting facing them. Makes it a little awkward especially if you want to just watch TV, or take a nap in your PJs.
If the flying time actually had to be used for (collaborative) work then that's a different matter. I've never had to do that though.