How do I change the image display duration in the Catalina screensavers? I am using macOS 10.15.2

I have tried: OS X Mavericks screensaver changes pictures too quickly: How do I slow it down? and it doesn't work. Then I tried: How do I control the image display duration in the Mojave screensavers? Here I can not find the mainDuration default of 3 (Points 6 and 7) and therefore not change it.

I would like to make the image duration screen saver different. Is this possible?
I stumbled upon this problem today. Even with 'csrutil' disabled I couldn't modify the screensaver. I found out Catalina double protect the user setting the volume as read only.
After disabling 'csrutil', do 'sudo mount -uw /' on terminal and you'd be able to modify it until restart.