Rookie team in need of scaling advice

[cantdecide]

Originally Posted by Ty Tremblay

I like to think about it in terms of effort required per point. Climbing is hard and is only worth a net gain of 10 points.

Kind of offtopic, but we recently had an argument about exactly that with my team. I argued that the gain was 10 points¹, but my teammate argued that it was 15 points².

¹: The game reveal clearly suggests that the 5 point bonus from challenging a tower is removed when you scale it, and the whole sum becomes 15 points(5 is crossed out and 15 takes its place). However:
²: As far as I can see the game manual only has a table(page 3 of the manual) which says that challenging is worth 5 points, and scaling is worth 15. It says nothing about the scaling bonus negating the challenging bonus.

Which one is correct? Can you provide sources?

Here's the part of the video that shows 5 getting replaced by 15.