How should I fill horizontal joints?

[S&N]

This picture shows two seams in our soon-to-be-renovated guest toilet that I need to spackle. I've tried reading up on how to do it, but I still feel uncertain... The vertical seam curves inward, and there I apparently need to glue a thin paper strip with wet room adhesive (Hernia KP4 with a dry content of 35%) and then continue with three layers of Bostik "Light Hand Spackle" until it's smooth, but the horizontal seam doesn't curve inward. Should that one also have a glued strip? Or is it enough to spackle where the carpenter has beveled the edges?

 

[sinuslinus]

You need a paper strip there too and then you should spread the plaster wide.

 

[S&N]

You need paper tape there as well and then you should spread the filler widely.

Thank you, I will do that!