when to cut a placement?

[kimi]

I want to know when is the right time to cut placements. I need two answers to this question.

1. When we get a new offer, we usually need to test a combination of creative and landing page to find a qualified conversion rate. During this stage, if we encounter placements with high costs but low or no conversions, we should cut them. So, what should this value be?

2. In the second round of testing, we already have a validated combination of creative and landing page. This stage is to test which placements can be profitable. So, for placements with what cost should we cut them?

Thank you in advance