[Q] loss due to patch cord and adaptor

Let me ask a question about coupling loss using two patch cords and
one adaptor (or mate). They could be FC/PC or FC/APC.
What kind of loss can we expect when we put them together.

I've just talked to one person in the company.
She said 
 1. termination loss due to patch cord imperfection. (<0.3dB worst
case)
 2. adaptor loss (0.1-0.2dB)

Can we calculate total loss by adding all of them ? 
For example, 0.3dB(1st patch cord) + 0.3dB(2nd patch cord) +
0.2dB(adaptor) = 0.8dB

What will be typical coupling loss for FC/PC and FC/APC in this case?

Is there any company that can make kind of low loss patched cord or
adaptor?

Thanks.