New ILs while already full flights

Is it worth to sign more ILs if i already have mostly 100% flights?

Yes and no.

  • Yes as it is always good to have as many partners as possible because they might be beneficial at some point and not sighing might appear as rude which might make your future relations cooler. 
  • No as long as you dont need these partners right now there is no need to pay the price. 

These are the two arguments and the choice is yours ;).

What kind of full?

Full of direct passengers? Or connecting passengers?

I would not sign up for any interlining when my flight is still 90% full of direct passengers.